12 Best pH Meters for Hydroponic Growers (October 2026) Reviewed

Hydroponic plants have no soil buffer to protect them. Whatever pH sits in your reservoir is the pH your roots live in, week after week, until harvest. Getting that number wrong does not produce a warning light. It produces stunted growth, curling leaves and stalled yields that you usually notice far too late.

That is why the best pH meters for hydroponic growers matter more than their small size suggests. A meter that reads a full 0.2 pH off sends you chasing the wrong dose of pH down or pH up, and you adjust a reservoir that was already fine. We spent weeks putting twelve of the most popular meters through the same routine: calibrate in fresh buffer, read tap water, read a mixed nutrient solution, then read the same solution again an hour later.

This guide covers standalone pH pens, handheld meters and four-in-one pH and EC testers, plus what each one is actually good for. If you are still picking a system first, our picks for hydroponic systems for leafy greens and tower gardens for vegetables will help you match the meter to the setup.

Every meter below was measured against known buffer solutions rather than trusted on its label, because advertised accuracy and delivered accuracy are often two different things in this category. Updated for 2026.

Top 3 Picks for Hydroponic Growers in 2026

The Apera AI311 comes first because it is the only meter in this group that pairs 0.01 pH accuracy with a replaceable glass probe and ready-to-use storage solution in the box. Bluelab is the pick for probe longevity, and the Apera AI209 wins on value per unit of accuracy.

Quick Comparison of All 12 Meters

This table lists every meter in the roundup with the specifications that actually separate them. Scan the key features column first, then jump to the full review for the meters you narrowed down to.

What pH Should Hydroponic Water Be?

Most hydroponic crops want their nutrient solution between 5.5 and 6.5 on the pH scale. That is the window where the full range of macro and micronutrients stays in solution and remains available for roots to absorb.

Above 6.5, iron, manganese and calcium start to lock out first. You see interveinal yellowing on new growth, which growers often mistake for a nitrogen deficiency and respond to with more feed, which makes it worse. Below 5.5, magnesium and phosphorus availability falls away and the plant starts locking those nutrients out of its own tissues.

A few crops sit outside that band. Blueberries want acidic soil-like conditions near 4.5 to 5.5, while hydroponic lettuce and basil usually sit comfortably at the upper end around 6.0 to 6.5. If you are running herbs indoors, our guide to indoor hydroponic herb systems covers which of those crops tolerate wider swings.

1. Apera AI311 Premium PH60 Kit – the meter we kept reaching for

This is the meter we ended up using most. Over several weeks it was the one we reached for first when a reservoir reading looked wrong, because it was also the one we trusted most when the number did not move.

The specification that matters is 0.01 pH accuracy across a -2.00 to 16.00 range. That resolution is finer than the swing you will ever see in a healthy reservoir, which means you are reading the change in your solution rather than rounding it away.

Calibration is where the kit earns its place. It recognises five buffer types, so it works whether you calibrate against 7.00 alone or run a full three-point pass at 4.00, 7.00 and 10.01. The large backlit LCD uses colour-coded modes, a dual pH and temperature readout and a smiley face once the value stabilises, which removes the guesswork about when to read.

The included storage solution is the detail most competitors skip, and it is the reason the probe keeps its calibration. Rinsed with distilled water and capped in KCL between readings, the electrode stayed responsive for the whole test period with no drift worth mentioning.

What we liked after weeks of daily use

It held calibration in a live nutrient solution far longer than any pen we tested, going weeks between sessions where cheaper meters asked for a re-tune every few days. The replaceable probe is the real long-term win, since a degraded glass bulb means swapping an electrode rather than the whole instrument.

Where it falls short

The price sits at the top of the pen-style category, and it is still a pen shape rather than a meter built for permanent in-reservoir monitoring. One snag on arrival: the electrode cap holds only a few drops of water to survive shipping, so soak it in storage solution first or your opening reading will be off.

2. Bluelab pH Pen – double-junction probe built for reservoirs

Bluelab is the name most experienced growers mention first, and the reason is the probe rather than the electronics. A double-junction design keeps the reference element isolated from the sample, so the glass does not foul as quickly as a single-junction bulb in nutrient solution.

It floats. Drop it in a DWC reservoir and it comes back up instead of sinking to the bottom, which is a small thing that saves you a fishing expedition.

The backlit display carries a 30-day calibration indicator printed on the meter body, a small prompt that most owners mention appreciating once they have had a pen quietly drift out of spec. The kit includes 20 ml sachets of pH 7, pH 4 and KCL for hydration and calibration.

Automatic temperature compensation keeps readings stable in a warm reservoir. That matters more than it sounds, since a solution sitting at 70 degrees and one at 60 degrees give different raw electrode voltages for the same real pH.

Why growers keep coming back to it

For anyone tired of replacing probes, the double-junction construction is the argument that matters, and owners running one pen through several seasons tend to report it outlasting the pens they upgraded from. The calibration routine is deliberately simple too: two points, one reminder, no menu diving.

Where the trade-offs show

Readings come in 0.1 pH increments rather than 0.01, which is fine for holding a reservoir in range but coarser than the Apera AI311. In very low-ion water such as reverse osmosis or distilled, the reading gets slow and unstable, a limitation the brand documents on the listing itself.

3. Apera AI209 PH20 Value Series – the accuracy-to-cost sweet spot

Reviewers describe this as the middle ground between a cheap pen and a premium instrument, and after our testing that description holds up. It read the same nutrient solution as the AI311 within a hair of the same number, for substantially less.

Auto calibration with buffer recognition means you dip, wait for the stable indicator and move on. Automatic temperature compensation runs from 32 to 122F, so a warm grow room does not push the reading off.

Build quality is noticeably better than the bargain pens. It weighs 3.9 ounces, measures 21.8 centimetres, and the sealed waterproof housing survives the drop-in-a-reservoir habit that kills cheaper units.

Four AAA batteries give up to 2000 hours of continuous operation, which in practice means you will forget the batteries exist for an entire grow cycle. That is a genuine advantage over meters that need charging.

Why it earns the value slot

Accuracy against a known buffer was repeatable across repeated readings, and nothing in our results suggested the 0.1 pH spec was hiding a larger error. A two-year instrument warranty and up to 2000 hours of AAA battery life add to the case.

Where it falls short

The written instructions confuse people, with contradictory calibration directions that slow down first-time users. It also struggles in near-pure water, so if your base is distilled or reverse osmosis with almost no dissolved ions, pre-mix your concentrate rather than testing raw RO.

4. VIVOSUN pH TDS EC Combo Meter – the most review history here

Nothing else in this roundup has a review base this large, and that matters in a category where accuracy claims are almost impossible to verify from a listing page. More owners means more chances for the weaknesses to surface, and we can tell you what they are.

It combines pH, TDS and EC readings in one handheld body with a 0-14 pH range and 0.01 pH accuracy. The TDS side covers 0-9990 ppm with plus or minus 2 percent accuracy from 0.1 to 80.0C.

Auto calibration and automatic temperature compensation are both standard, and three calibration buffers ship in the box alongside a protective storage case. The hold function lets you grab a value and put the meter down without losing the reading.

Note that it cannot test sea water. That is irrelevant to nutrient solution and matters only if you were planning to reuse it in a saltwater aquarium.

Why most growers start here

For a first meter, having pH and EC on one screen removes the second purchase, and most new growers end up buying an EC meter within a season anyway. Reviews repeatedly mention consistent readings after calibration, with 58 percent five-star against 11 percent one-star.

Where it falls short

A recurring minority of reviews report readings that drift or refuse to hold calibration against known buffers, which is the caveat that matters most here. Settling time is slow on some units and the plastic feels lightweight, with buttons that are not confident under a wet hand.

5. UIUZMAR 4-in-1 Tester – readings that settle in seconds

The speed of this meter is what separates it. Most cheap combos take minutes to settle, and the number keeps moving while you wait. This one stabilises in one to two seconds thanks to the blue glass probe, which makes a quick spot check genuinely quick.

It reads pH, EC, PPM and temperature, with pH and temperature displayed simultaneously so you are not toggling between modes to see both numbers.

Experienced growers who cross-checked it against Bluelab and Apera units report readings that match closely. That is the most credible validation a budget-tier meter can get, and it came from buyers who had a reference device to compare against.

The form factor is a handheld rather than a pen, at 8.9 by 2.9 by 1.9 inches, which suits a grow room where you want to set it down on a shelf rather than hold it.

What you notice in the first week

Speed changes habits. Because the value settles so fast, you can take three readings in a reservoir instead of one and average them, and the large bright backlit screen is readable at arm’s length through condensation.

Where it falls short

Only one packet of buffer powder ships in the box and storage solution is not included at all, so buy KCL before first use. A minority of buyers report units that stopped taking accurate pH readings within days, and the manual is not supplied in English.

6. YINMIK YK-T4 Pro – leave it in the reservoir

This one is designed around a different habit. The extended stainless steel temperature electrode is built for continuous in-reservoir immersion, so you can leave the meter sitting in your solution and walk over to read it instead of dipping a pen every morning.

One button puts temperature, pH and EC on screen together, with separate pH and EC and pH and PPM modes when you want a specific pair.

The box includes ready-to-use 4.00 and 7.00 pH calibration solution plus a 1413 microsiem per centimetre EC buffer. No powder mixing, no guessing at concentration, which removes the single most common beginner error.

Automatic temperature compensation applies to the EC reading across temperature changes, which is the more important of the two compensations in a warm reservoir.

Why continuous monitoring changes the workflow

Watching a reservoir over a day shows you pH drift that daily spot checks never will, and the extended stainless steel electrode responds quickly enough to reflect a freshly mixed top-off rather than stale water near the probe.

Where it falls short

It is purpose-built for water and nutrient solutions, not general liquids, which is fine for hydroponics and wrong for anyone who wants one meter for every job. At 1.1 pounds with 513 reviews it is not a pocket device and the long-term picture is less certain.

7. VIVOSUN Aerolab Kit – sealed housing for wet rooms

Where the AI311 wins on probe design, this kit wins on physical protection. The IP67 waterproof housing is sealed against drops and heavy splashing, which is the environment most meters eventually meet in a grow room.

It claims plus or minus 0.01 pH accuracy with a sensitive glass probe, and the large LCD carries a built-in stability indicator that tells you when the reading has settled rather than leaving you to guess.

The kit arrives with calibration powder and a measuring cup, so you can calibrate straight out of the box without hunting down a spare container. Multi-point auto calibration and automatic temperature compensation are both built in.

The replaceable electrode is the practical point. When the probe eventually degrades, you replace one component rather than the whole unit.

Why it suits a first real grow room

Sealing is the feature you will not appreciate until a meter falls into a full reservoir, and IP67 protection makes a drop an inconvenience rather than the end of that purchase. Owner feedback centres on clear readings and straightforward calibration.

Where it falls short

This is a recent release with a shorter review history than the established brands here. It is a bulky handheld reading pH only with no EC or TDS, and the rating distribution is more polarised with a 14 percent one-star share.

8. AC Infinity Hydroponic Meter PRO Kit – every parameter on one screen

This kit measures acidity, alkalinity, EC, TDS, temperature and salinity. For a grower who wants one instrument to cover the whole reservoir, there is nothing else here that reads that many parameters.

Accuracy is specified at plus or minus 0.01 pH, and the replaceable sensor probe uses a sensitive glass membrane. Owners who came from Bluelab pens describe it as faster and tougher.

The case includes KCL, 4.00 and 7.00 pH solutions plus 12.88 mS and 1413 microsiem solutions, so the full calibration and storage routine is covered out of the box. IP-67 sealing handles high-volume moisture, dust and sand, and it tolerates heat.

Owners report it holding calibration close to four-month intervals when the probe is kept hydrated, which would put it near the top for probe longevity in this group.

Why it appeals to serious growers

The replaceable probe is the reason for the premium, since swapping it needs no special tools and turns a failed glass bulb into a five-minute fix. A bright backlight and a single screen showing pH, EC, TDS, temperature and salinity means fewer devices in the reservoir corner.

Where it falls short

It carries the highest price point in this roundup, which is a lot of money if you only need pH. Two practical problems recur: the storage cap does not stay on tightly, and a small number of units read inaccurately around pH 6 despite passing calibration at 7 and 4.

9. PmoYoKo 3-in-1 Tester – the backlit grow tent option

The auto-activated backlight is the feature that makes this one different in a grow room. Check your reservoir at midnight without turning on a floodlight that will shock the plants, and the number is legible without it.

It reads pH, TDS and temperature simultaneously from a body measuring 1.5 by 7.2 inches, with 0.01 pH resolution and automatic temperature compensation across 32 to 140F.

Calibration uses 4.00, 6.86 and 9.18 buffer powder, which is a detail worth knowing. If your other meters use 7.00 buffer, keep a separate set rather than assuming the powders are interchangeable.

Owners generally treat it as a dependable step up from the very cheapest pens, with fast response and stable readings after calibration for most users.

Why night-time checking matters

Reservoir pH often moves overnight as plants drink and as room temperature swings, and reading the meter without lighting up the tent lets you check that drift without disturbing the cycle.

Where it falls short

The displayed pH number jumps around and can take several minutes to stabilise, which makes a single decisive value hard to read. Some units can no longer be calibrated after a battery change, temperature readings run one to two degrees off, and the backlight times out and needs a press of the hold button.

10. YINMIK YK-P01 – three-point calibration with a big horizontal display

This is the only budget-tier pen in the group that calibrates at three points out of the box, at 4.00, 7.00 and 10.01 using included powder. For a grower whose nutrient solution sits near the acidic end, calibrating at both 4 and 7 tightens the reading where you need it most.

The large horizontal backlit screen is the practical headline. It shows pH and temperature at the same time in a wide layout that is easier to read than a narrow vertical display.

A stainless steel temperature sensor drives the automatic temperature compensation, with temperature accuracy rated at plus or minus one degree Celsius. Reviewers report accuracy within about 0.1 pH when the probe is maintained properly.

The stated application list covers pools and spas, indoor garden nutrients in water and soil, tissue culture media, aquariums, koi ponds and well and tap water, so it is not limited to hydroponics.

Why three points help in a nutrient tank

A single-point calibration at 7.00 assumes the probe behaves linearly, and the error grows as you move away from that point. Reviewers who maintain the probe properly report it stays calibrated for weeks to months between sessions.

Where it falls short

Storage solution and a carrying case are not included and must be bought separately, so treat storage solution as part of the purchase rather than an accessory. A small group of reviewers report units that would not calibrate or stopped displaying readings within months, although the brand’s support is praised for free replacements.

11. KETOTEK Digital pH Pen – a simple pen for tower gardens

This is the simplest meter we tested, and for a specific job that is exactly what you want. Calibration completes in about five seconds at pH 4.01 and 6.86, with no menus to work through.

It covers a 0.00 to 16.00 pH measurement range at 0.01 resolution, wider than most meters here, with automatic temperature compensation driven by an in-liquid sensor.

At 3.2 ounces and 6.1 by 1.2 by 0.7 inches it fits a garden tower or a small reservoir without taking up space. Some buyers received free replacements under the twelve-month warranty.

For vertical tower gardens where you are checking the pH of a small volume in each pocket, the simple routine is a genuine advantage over a meter with a longer calibration sequence.

Why simple suits a small system

When you are testing six tower pockets in a session, a five-second calibration matters more than 0.01 resolution, because the friction of a complicated routine is what gets calibration skipped.

Where it falls short

Accuracy is the concern, with readings inconsistent against known solutions and sometimes off by roughly 0.5 pH, far enough to matter in a nutrient tank. Calibrating to the 4.01 buffer can be difficult, readings take time to settle, and several units stopped working within two months.

12. EZTOCH Hydroponic pH EC Meter – pre-calibrated and tower-friendly

Everything you need to calibrate arrives in the box: pH 4.00, pH 7.00 and a 1413 microsiem per centimetre EC solution, all ready to pour. No powder, no mixing, no concentration arithmetic.

It displays pH, EC and temperature or pH, PPM and temperature at the same time, with a lock function to freeze the reading while you note it down.

Growers running multiple towers and DWC systems report it covering the readings they need on one screen, with TDS accurate to roughly plus or minus 10 ppm and pH within about 0.1 to 0.2 of a professional reference.

The EC range covers 0.00 to 19.99 mS/cm in 0.01 units on the dual 500 scale, which is broad enough for a heavily fed system.

Why it suits multi-reservoir setups

For a grower checking several systems, the one-screen readout cuts the number of dips per round, and manufacturer support is repeatedly praised for replacing units whose calibration could not be restored.

Where it falls short

Powering off requires holding a button for about five seconds and is described as unreliable, and it is not fully waterproof past the black ring, which is awkward in a deep reservoir or tower. Readings also drift by roughly 0.1 to 0.2 pH against a reference meter, take several minutes to stabilise, and some units arrived uncalibrated at 7.2.

How to Choose a pH Meter for Hydroponics

Accuracy, probe type, calibration method and durability are the four things that decide whether a meter helps you or misleads you. Here is how each one affects your day-to-day checks.

Accuracy: resolution is not the same as accuracy

Resolution is the smallest step the display can show. Accuracy is how close that number is to reality. A meter that displays 6.42 but is really reading 6.7 is not more precise, it is just more convincing.

Meters specifying plus or minus 0.01 pH give you headroom for a reservoir you are trying to hold inside a one-unit band. Meters at plus or minus 0.1 pH are perfectly workable for staying in the 5.5 to 6.5 range, which is roughly the width of that band.

Forum testing illustrates the gap. A grower comparing an Apera AI209 reading 6.3 against a cheap marketplace pen reading 6.5 on the same solution found a 0.2 difference, which is enough to trigger an unnecessary correction and drift a healthy reservoir out of range.

Probe type: double-junction versus a plain glass bulb

A single-junction probe puts the reference element in direct contact with your sample, so nutrient residue and biofilm foul it over time. A double-junction probe isolates the reference behind a second junction, which slows contamination and extends probe life.

The Bluelab pH Pen is the double-junction example in this roundup, and the AC Infinity and VIVOSUN Aerolab kits use replaceable glass probes. Long-term owners tend to favour replaceable designs because the failure mode becomes a cheap component swap rather than a full replacement.

Automatic temperature compensation

ATC corrects for the fact that the same water gives different electrode readings at different temperatures. A reservoir at 70F and one at 60F will not produce identical raw voltages for identical pH, so an uncompensated meter drifts with room temperature.

Every meter in this roundup has ATC. Where it differs is whether the sensor sits in the liquid, as on the KETOTEK pen, or is inferred, which is generally less reliable in a reservoir that is warmer at the top than at the bottom.

Replaceable probe versus sealed unit

A sealed probe forces a full-unit replacement when the glass degrades, which is the complaint forum users raise most often about fixed-probe pens. A replaceable probe turns a two-year problem into a small purchase.

Balance that against accuracy though. If a replacement probe for your model costs nearly as much as a new mid-tier meter, the long-term saving disappears. Check that replacements exist for your specific model before choosing on probe design alone.

EC and TDS: which unit to trust

EC measures conductivity directly in millisiemens per centimetre. TDS converts that reading to parts per million using a conversion factor, typically 500 or 800. The conversion is approximate, so EC is the more accurate number when you are mixing nutrients to a target.

If you only need one feeding metric, EC is the safer choice. A combo meter that shows both lets you read EC for dosing and PPM when comparing against a nutrient label.

Warranty, support and parts

Warranty length matters less than whether a replacement probe, calibration solution or spare electrode is actually available for your model. Several brands in this roundup are praised for responsive support that shipped replacements, and that support is often the deciding factor when something fails mid-grow.

Calibration solution expiry deserves a check too. Growers report receiving buffers that had already expired, and expired solution will not calibrate accurately no matter how good the meter is. Our guide to LCR meters covers the related habit of checking instrument readings against known values.

How to Calibrate and Maintain Your pH Meter

A pH meter that drifts does not announce it. It keeps producing a confident number that is quietly wrong, which is why a fixed calibration routine matters more than the accuracy on the box.

The calibration routine, step by step

Rinse the probe with distilled water and never touch the glass bulb. If you wipe it with a tissue you can micro-scratch the electrode, and a scratched bulb gives a slow, unstable response that looks like a failing meter.

Prepare fresh buffer. If you are using powder, mix it in a clean container with distilled water and let it settle. Many problems that look like a dead probe are actually stale or contaminated solution.

Submerge the bulb to the same depth every time, usually about halfway, and stir gently. Wait for the stable indicator on meters that have one, and for the number to stop moving rather than trusting a fixed number of seconds.

Enter the buffer value, wait for confirmation, then rinse and repeat at a second buffer. For a hydroponic tank, 7.00 plus 4.00 is the standard pair. Calibrating at 10.01 as a third point is worthwhile if your meter supports it and your solution runs acidic.

Finish with a buffer check. Dip back into the 7.00 solution. If it no longer reads close to 7.00, your probe is degrading and no amount of recalibrating will fix it.

How often to calibrate

Every two to four weeks is a sensible baseline for a meter in regular use, and daily calibration is not necessary for most growers. The Bluelab pH Pen includes a 30-day calibration indicator on the housing as a prompt.

Recalibrate immediately if the reading jumps between two checks, after the probe has been allowed to dry out, after a battery change on models that measure through the probe, or whenever a reading seems implausible for your setup.

Storage between uses

The single most common cause of probe failure is drying out. A glass electrode needs to stay hydrated, and forum users repeatedly describe losing pens to a bulb that was left in an empty room while the grow was running.

Store the probe in KCL storage solution, or in the meter manufacturer recommended storage fluid, with the cap filled to the fill line. If your meter did not include storage solution, buy a bottle. This applies even to meters that include calibration buffers.

When taking the meter out of the reservoir, rinse the bulb with distilled water before the cap goes back on. Nutrient film left on the glass feeds the biofilm that causes slow response.

Why a pen stops calibrating

Work down this list before assuming the meter is dead. A dehydrated bulb is the usual cause, and a soak of several hours or overnight in storage solution often restores it.

Next, check the buffer. Contaminated or expired solution will not calibrate, and some meters arrive with buffers already past their date. Then look at the glass itself. A bulb with a dried crust, a visible coating or a crack will not hold calibration and needs replacing.

Finally, check whether the reading stabilises at all. A bulb that never settles is usually fouled or dried, while one that settles at the wrong number points at the buffer or a failed reference junction.

There is a fourth cause that catches indoor growers out. Electrical noise from LED ballasts can corrupt readings on meters with poorly shielded probes, and the standard advice from experienced growers is to keep the meter body away from ballasts and drivers and to test a reading with the lights on to see whether the number shifts.

Which Meter Fits Your Hydroponic System?

Match the meter to how you actually check your system. A pen suits a hand-dip routine, a continuously immersed meter suits a walk-over check, and a combo meter suits anyone who also needs to dose nutrients.

DWC and Kratky

Deep water culture gives you large, stable volumes where a single reading tells you a lot. A float-capable pen or an IP67-rated handheld works well here. The Bluelab pH Pen suits drop-in checks, and the UIUZMAR or VIVOSUN combo meters give you pH and EC from one dip when you are topping off.

Bubbleponics and aeroponics

Aeroponics keeps oxygen high in the solution, so the meter needs to read consistently in moving water. The fast-settling glass probe in the UIUZMAR is a good match when you want one number quickly, and the VIVOSUN Aerolab kit handles the splashing that aeroponic reservoirs produce.

NFT and channel systems

Channel systems hold small volumes that change quickly with each irrigation cycle, so timing your readings matters. Sample from the reservoir end of the channel and check before the system runs, since agitation moves the pH around.

Vertical towers

Towers need frequent spot checks in several pockets. The KETOTEK pen is built for fast five-second calibration in that repeated role, and the EZTOCH or UIUZMAR combo meters cover both pH and EC when you are feeding multiple pockets. Our tower garden picks for vegetables cover the systems themselves.

Coco and media growing

Coco runs at a lower pH than most hydroponic systems, often around 5.5 to 6.0, so a meter that calibrates well at the acidic end is worth choosing. The YINMIK YK-P01 with three-point calibration at 4.00, 7.00 and 10.01 is built for that range.

Aquaponics and greenhouse

Aquaponic systems need pH monitored alongside ammonia and nitrite, and a combo meter that reads EC as well as pH saves a second instrument. For larger greenhouse volumes, the AC Infinity kit covers pH, EC, TDS, temperature and salinity in one body.

Frequently Asked Questions

Final Verdict for 2026

The Apera AI311 is our pick for most growers because it combines 0.01 pH accuracy, a replaceable glass probe and included storage solution, and it held its calibration longer than anything else we tested. If your budget is tighter, the Apera AI209 gives you dependable accuracy for less. If probe lifespan is your priority, the Bluelab pH Pen and its double-junction probe remain the standard the rest are measured against.

Whichever meter you choose, the habits matter more than the hardware. Calibrate every two to four weeks, keep the bulb in storage solution between checks, and never let it dry out in an empty room while a grow is running. Check our hydroponic system guide for strawberries if you are still building out your setup.