API calcium test malfunction??

[KidReefer]

Ok so my tank is around a month and a half old, I am doing kalk in the ATO( 1tsp per gallon) and to get the calcium adjusted aquac complete 2 part. I have a low coral count, 3 LPS and 1 GSP. I have been doing this routine for around 2 weeks and my last test at the LFS was 400.

After, to save me the time of going to the LFS I bought a API test kit, and it always gives me a low test result, but I thought the calcium was actually that lvl. However this morning I tested calcium and got 360 then added 4 tsp of AquaC complete part A and B. It says an hour to wait for mixing but I waited around 5 just to be sure, and when I tested I got 300. To me this makes no sense at all. On the directions it says dont use another calcium/ alk buffer( in my case kalk) or it will cause a ionic imbalance. Do you think this could be causing the weird test kit results??

Hopefully someone will be able to shed some light on this

[disc1]

I think maybe there is a mistake running the test. How much titrant was required to get to the end point on both tests? Are you maybe reading it backwards?

Even if the kit was bad, it would still take more titrant after adding calcium than it did when you tested before. At worst you would use the same amount and get the same number.

[KidReefer]

I dont believe I did the test wrong but if I did then hey, you learn everyday :)

I think I know what a titrant is and if Im right its 5ml of my tank water(measured by using the marked indicator) and 10 drops of the first solution, the second solution 15 drops then one individually until it turns colorwise from pink to a blue/purple.

So i did in total 5m+28 drops on the first test and 5ml+15 drops in the second.

[disc1]

The reason I asked is because the instructions on some kits read the position of the piston in the syringe and some read the amount of added titrant and the difference can get confusing especially if you changed brands of kits.

Something is obviously throwing that test off. There's no way you lost that much calcium that fast even if you weren't adding it, much less if you were.

[KidReefer]

yeah i think its just a bogus test kit, Ill just take it back to the LFS and get a new one and see if that one works correctly. Im getting coralline growth on the dry rock in my tank so i take that as a sign the calcium is okay for now. Thankyou very much for the help!!