Nitrates increasing alk?

[russell.dexter]

Hello all,

I've recently added sps corals to my 40 breeder and made the decision to use Tropic Maurin's All for Reef for dosing calcium and alkalinity to keep things simple. I do this with an auto doser at 3mls per day. I continue to notice that my calcium level drops over the course of a week, although I have dialed my alk at 9dKh. (I test Alk every other day using a hanna tester and it ranges 8.9 -9.0 each time) I have been manually adding brightwell's calcion every week to bring the calcium levels back to 430ppm. (To the order of 10 -20mls in one dose.) (Note I use red sea tests for calcium and magnesium)

I have struggled with low nutrients since starting the tank two years ago and have only recently seen decent growth by dosing Brightwell's neo phos at 11 mls per day and neo nitrate at 5mls per day. This keeps my phosphate at 0.02ppm (hanna ultra low phosphate checker) and my nitrate at about 10ppm (salifert) Before I dosed nutrients I had slow growth with all soft corals and the one sps stick in the tank was pale and did not grow at all. I also struggled with chrysophytes / dinos to no end (confirmed with a microscope I bought to diagnose the slime)

Nitrate, phosphate and All-for-Reef are on dosers to spread the dosage out over 12 times per day.

I have also read that dosing nitrate can increase Alkalinity, which I realize now is probably the root cause of the tank seeming to use more calcium than alkalinity.

I know my goal is stability so therefore wonder if All-for-Reef would be the best choice for my tank's particular set-up or if I should switch to two part. (My goal is to automate with dosers to a reasonable extent)

Do corals tolerate the sudden changes in calcium content versus alkalinity better? (I am wondering if making just one adjustment per week using the calcion is not ideal)

Thanks for any feed back

Current Parameters:
Salinity 1.026
Calcium 430 (dosed calcion today- was 380)
Magnesium 1400 (dosed 5mls of magnesion today as well)
Alkalinity 8.9
Phosphate 0.02
Nitrate 10

 

[Miami Reef]

Every 50ppm consumed from dosing nitrates adds 2.3dKH alkalinity; it isn’t really that much.

Adding food or dosing ammonia initially depletes alkalinity, but that same alkalinity will come right back once the nitrates or ammonia gets consumed, so that process is net 0.

Dosing nitrates bypasses the initial alk depletion.

 

[Miami Reef]

Corals consume calcium and alkalinity in a fixed ratio: 2.8dKH per about 20ppm calcium. Is your tank having that sort of demand? Calcium test kits aren’t really that precise.

 

[russell.dexter]

Thank you for the feedback

I don’t think it’s possible for my tank to have that much of a demand - and as per your calculation there would be a slight offset because I’m dosing nitrate - but really not any amount to speak of

I’m going to retest the parameters tomorrow, now that I have made the adjustments, and test several times this week to check the uptake

 

[Randy Holmes-Farley]

If you have an imbalance for any reason and calcium is dropping below your target, it is fine to add calcium chloride to bring it back up. It is not important to keep calcium fixed at some amount. 400 - 550 ppm calcium are all equally fine, IMO.