API Freshwater Master Test Kit

The API Freshwater Master Test Kit is the liquid test kit most freshwater keepers end up owning. It covers the five parameters that actually tell you whether a tank is safe, and liquid reagents read truer than strips, which is why it stays the shop standard for diagnosing a sick tank or tracking a cycle. Browse all of our water testing.

What It Tests

• pH and high range pH, so you can read both ends of the scale
• Ammonia, the first thing to spike in a new or crashing tank
• Nitrite, the second stage of the cycle and just as lethal
• Nitrate, which tells you whether your water change schedule is keeping up

API says the kit measures these with scientific accuracy for professional results, and recommends testing weekly.

What's in the Box

• Seven bottles of liquid test reagent
• Four glass test tubes with caps, in a holding tray
• Computer-calibrated laminated color card
• Step-by-step instruction booklet

API markets this as an 800-test kit, so a single box lasts a typical hobbyist a long time.

How to Use It

• Rinse the tube in tank water, fill to the line, add the drops the booklet specifies, cap and invert.
• Read it against the color card in natural light, holding the card behind the tube with a white background.
• Shake nitrate bottle #2 hard for the full time the booklet calls for. Under-shaking that bottle is the most common cause of a falsely low nitrate reading.
• Test weekly once the tank is settled, and daily while cycling or after a problem.

Specifications

Pairs Well With

• API Saltwater Master Test Kit if you also run a marine tank.
• Seachem Prime, which detoxifies ammonia and nitrite while you fix the cause.
• Browse all of our test kits.

Frequently Asked Questions

Why liquid instead of strips?
Liquid reagents are more precise and far less prone to the false readings strips give once they have been exposed to humidity. For diagnosing an actual problem, liquid is what you want.

My nitrate always reads zero. Is that right?
Usually not. The nitrate test needs bottle 2 shaken hard for the full time the instructions state, and the capped tube inverted for the full time as well. Skipping that reads low.

Do the reagents expire?
Yes. Each bottle carries a lot and date code. If a kit has been open for years and readings look impossible, replace it before you chase a problem that is not there.

Does this work for saltwater?
Use the Saltwater Master Test Kit instead. The ammonia, nitrite and nitrate chemistry differs for marine water, and the freshwater color cards will not read correctly.