pH, EC & TDS Water Test Meters
Quick Bloom Lights stocks water test meters for anyone who needs a reliable number on their water: pH pens, EC and TDS meters, all-in-one testers that read pH, EC, TDS, salinity and temperature from one probe, a drop-test pH kit, and an in-tank sensor that logs readings around the clock. The range covers AC Infinity, AZ Instrument and Hy-Gen, from simple spot checks to continuous monitoring. Everything is stocked in Sydney and shipped domestically.
±0.01 pH
AC Infinity PRO pens
5 readings
pH, EC, TDS, salinity, temp
IP65–IP68
water-resistant to submersible
3 brands
stocked in Sydney
pH and EC: the two numbers that matter
pH decides which nutrients the roots can actually take up. Outside the right window, nutrients are in the water but locked out of the plant, which is why so many deficiency symptoms turn out to be a pH problem rather than a feeding problem. EC (electrical conductivity) tells you how strong the nutrient solution is; TDS (ppm) is the same measurement converted to a dissolved-solids figure. The two are separate measurements and need a meter that reads each. Test after every mix, after topping up, and check run-off to see what the root zone is doing.
The same meters are used well beyond growing: aquariums and ponds, pools and spas, rainwater tanks, home brewing and general water treatment.
The range at a glance
| Product | Reads | pH accuracy | Best for |
|---|---|---|---|
| AC Infinity pH Meter Kit | pH, temperature | ±0.1 | Occasional checks, one reservoir |
| AC Infinity pH Meter PRO Kit | pH, temperature | ±0.01 | Daily testing, replaceable probe |
| AC Infinity Hydroponic Meter PRO Kit | pH, EC, TDS, salinity, temperature | ±0.01 | One pen for both pH and nutrient strength |
| AC Infinity AI Hydro Sensor | pH, EC, TDS, salinity, temperature, logged 24/7 | — | Continuous monitoring and automation with the Controller AI+ |
| AZ Instrument 8685 pH Pen | pH, temperature (ATC) | ±0.2 | Budget pH pen with 3-point calibration |
| AZ Instrument 8362 EC & TDS Pen | EC, TDS, temperature (ATC) | n/a (no pH) | Nutrient strength and tap water checks |
| Hy-Gen Complete pH Kit | pH by colour, plus pH Up and Down | within 0.5 | No batteries or calibration; a backup to any meter |
AC Infinity pH and hydroponic meters
The AC Infinity pH Meter Kit is the entry point: a lithium glass membrane probe reading pH and temperature to ±0.1, sealed to IP67, with 4.00 and 7.00 calibration solutions in the box. The AC Infinity pH Meter PRO Kit tightens that to ±0.01 and makes the probe interchangeable, so when it wears out you replace the probe rather than the whole meter. The AC Infinity Hydroponic Meter PRO Kit adds EC, TDS and salinity to the same pen, so one probe covers pH and nutrient strength.
Continuous monitoring: AC Infinity AI Hydro Sensor
A pen tells you what the tank is doing at the moment you test it. The AC Infinity AI Hydro Sensor sits in the reservoir and logs pH, EC, TDS, salinity and water temperature to the app around the clock. Paired with the AC Infinity Controller AI+, those readings can trigger dosing pumps, top-ups and alerts. It needs the Controller AI+ and does not work with the Controller 69 line.
AZ Instrument pens
AZ Instrument is a Taiwanese maker of water quality and environmental meters. The AZ 8685 pH Pen reads pH to ±0.2 with automatic temperature compensation and up to 3-point calibration. The AZ 8362 EC & TDS Pen is a conductivity meter with auto-ranging up to 160 mS and an adjustable TDS factor, so its ppm readings can be matched to the scale your nutrient chart uses. Both run on 4 × LR44 batteries and carry an IP65 rating.
Drop-test pH: Hy-Gen Complete pH Kit
The Hy-Gen Complete pH Kit tests pH with an indicator solution and a colour chart, accurate to within 0.5 pH, and includes 150 mL each of pH Up and pH Down to correct it. No batteries, no calibration, nothing to dry out. It is a simple way to start, and a useful cross-check if a meter reading ever looks wrong.
Accuracy depends on calibration. Any electronic pH or EC meter drifts over time. Calibrate on arrival, then regularly (monthly for regular use) and whenever a reading looks wrong. Keep pH probes wet in their cap between uses; a glass electrode left to dry out is the most common way pH pens fail.
FAQ
Do I need a pH meter and an EC meter?
For hydroponics and coco, yes: you need both numbers. Either buy two pens (for example the AZ 8685 and AZ 8362), or one AC Infinity Hydroponic Meter PRO Kit that reads both from a single probe.
What is the difference between EC and TDS?
They come from the same conductivity measurement. EC is the direct reading; TDS (ppm) is EC multiplied by a conversion factor. Different charts use different factors, so check which scale your nutrient brand uses, or work in EC to avoid the confusion.
±0.01 or ±0.1: does it matter?
For nutrient solutions, ±0.1 is enough to keep pH in range. ±0.01 matters more for daily users who want to see small drift early, and for applications such as aquariums and brewing where tighter control is useful.
How long does a pH probe last?
The probe is the wear part on every pH meter. AC Infinity give an average probe life of about 18 months; AZ Instrument rate their sensors at more than 6 months with good maintenance. Storage and calibration habits make the biggest difference. On the AC Infinity PRO pens the probe can be replaced on its own.
Can I leave a pen in the reservoir?
No. Handheld pens are for spot testing. For a probe that stays in the water, use the AC Infinity AI Hydro Sensor, which is IP68 and built to stay submerged.