My test kit odyssey and some data

[rocketeer]

I wasn’t sure if I should post this in vender/product experiences or here. I put it here because I want lots of people to know what I found. My tank chemistry has been driving me nuts. I have been getting widely varying results from test kits so I decided to use my vast collection of tests on some freshly mixed Red Sea Coral Pro salt mix.

Alk:
Label on can: 4.3 Meq/L
API: 4.25 Meq/L
Salifert: 3.75 Meq/L
Seachem: 3.5 Meq/L
Red Sea: 3.0 Meq/L

Ca:
Label on can: 450 ppm
API: 445 ppm
Tropic Marin: 425 ppm
Salifert: 415 ppm

Mg:
Label on can: 1340 ppm
Tropic Marin: 1280 ppm
Salifert: 1275 ppm

I know it’s not real scientific, since it’s only one test, the label on the can doesn’t really make it a good standard, and there aren’t very many brands represented, but it’s data we can use.

Here’s my odyssey that led me to do this. I do 30 gallon water changes weekly on about 240 gallons of water with Red Sea Coral Pro Salt. For months I have been getting alk readings between 2.4 and 3.0 Meq/L with 3 out of 4 test kits, and API comes in between 3.6 and 4.0 Meq/L so I considered it an outlier. In trying to raise my Alk I started dosing more and more with BRS Soda Ash. When I dose I always get a snow storm, so I had to dose more Ca as well. A Red Sea test kit that measured Mg too high allowed me to get very low on Mg (1160-1200 with Tropic Marin and Salifert). So I dosed a gallon and a half of B-Ionic Mg supplement to get it to 1300-1350 range hoping that would stop the snow storms. The snow storms persist and I am dosing ½ gallon each of CaCl and Soda Ash solution every day getting nowhere. I can’t raise my Alk. I am taking out over a gallon of tank water every day to keep my salinity in check, losing trace elements along the way.

It turns out that my OUTLIER, API, was the most accurate test kit and Salifert, Red Sea and Seachem have probably almost crashed my tank. That changes everything!

Jack

[Zack]

Api has some pretty accurate mg ca and alk but their nitrite and nitrate tests are terrible from my own experience. I'd love to see these results with a Hannah checker to see how the brands stack up.

[Justin]

Also check the date of your tests. If they are expired, it will throw off your results.

[leliataylor]

Jack, I have found the same results when comparing different test kits. I have also found some test may be accurate at one level and give crazy results at higher or lower levels. For example API nitrite and ammonia kits do well below .25 ppm, however they yield some crazy readings at higher levels and in some instances they have yielded results that were not on the color chart i.e. turning purple when the solution is first added and green after 5 minutes on a nitrite test. A Salifert Mg kit gave me readings of less than 1500 when I was dosing Kent Tech-M daily to eliminate Bryopsis. The Bryopsis is gone, however it should not be based on the Mg readings I was getting. Another one of my favorites dKh/Alk never changing and Ca always being too low even after adding Ca with Salifert kits.

I really am not impressed with any of the kits I have used.

[rocketeer]

It's amazing we can keep corals at all when people recommend a range about .5 Meq/L wide and test kits vary by 1.25 Meq/L.

Jack

[rocketeer]

Oh yeah, they're up to date. Thanks.

Jack