What to test for

Saltwater-Newfie · Jul 21, 2022

Hello all. I am in the process of collecting new kits as the only ones my LFS sells are the API ones and that is what they use to test any water samples. I know of Hanna, Salifert, Red Sea and I know there are a few others out there. With a tank that has fish and corals what kits should I look at/for and what should I be testing for? Links to Canadian sellers would be a plus.

Gtinnel · Jul 21, 2022

Once a tank is done cycling all I regularly test for are nitrates, phosphates, alkalinity, calcium, and magnesium.
Calcium and magnesium I use Red Sea
For the others I use Hanna.
I also use a trident for automated testing of alk/cal/mag.

shakacuz · Jul 21, 2022

new tank after cycling/no fish or corals: definitely po4/no3 are priorities.
tank with corals and fish: alk/cal/mag/salinity, as well as no3/po4.

i use hanna for ph, alk, cal, no3, and po4. aquaforest for mag.
i have secondary test kits just to double check; red sea no3/po4/alk/cal/mag.

PatW · Jul 21, 2022

Like everything, it sort of depends….

Something to be able to test of reliably is salinity. I use a refractometer and I have calibration fluid. Also, it is really good practice to have an auto top off on your tank. An ATO will keep salinity in a pretty narrow range and marine organisms LOVE LOVE LOVE stability.

When you cycle a tank, you measure ammonia, nitrite and nitrate until ammonia and nitrite go to zero.

Since I have cycled my tank, LO these many years ago, I have not measured ammonia or nitrite.

I do keep tabs on nitrates. The color changes in API for nitrate kinda drive me crazy. I use Red Sea Pro but Salifert is OK (and cheaper) and Hanna HR has really nice reviews but I have not fooled with it.

It is good to have an idea of what your phosphates are and pretty much only Hanna ULR tests low enough to be useful. I use ULR phosphorous because it is a bit more sensitive than ULR phosphate.

Now we come to the BIG THREE: ALK, Ca and Mg. If you are running a tank with fish, soft corals and a cleanup crew, you really will not have much of anything consuming ALK, Ca and Mg unless you get a bunch of coralline algae growing. Water changes just might be good enough to keep everything good. ALK is the most critical of the three. It depletes the fastest and a lack of it can cause a tank crash.

But in a low consuming system, measuring once per week should be plenty. I would say Salifert for all three is good. Red Sea for Ca and ALK. Hanna has a good ALK test.

If you have stoney corals especially if you have a bunch of SPS corals, you will need to measure ALK daily and probably dose ALK and Ca and maybe Mg. And with hand dosing, you probably should be using a doser also. I don’t think you will have this problem for awhile (if ever).

Then there are trace elements. And measuring them is rather problematic for the reefer. You can send samples of your water off to outfits that will test virtually everything. You can dose trace elements based on your ALK and Ca consumption but that is rather crude. Or you can just use the good old BRUTE FORCE technique of regular water changes which is quite probably the most reliable method.

Oh, if you run chaeto in a refugium to keep nitrates and phosphates in check, it can deplete some trace elements And once that happens it dies. I have had good luck with dosing Chaetogro (which is a brew of stuff that chaeto consumes but again dosing like this is CRUDE but ya do what ya have to).