Two Part Dosing - Drop in CA

[skidrow52]

Hi I use BRS's two part dosing system and since a few months I am seeing a good growth in my SPS corals eventually I had to increase the daily dose which is dosed using a dosing pump every hour, in 24hours i dose 95ml of both CA and ALk solutions which had been kept my CA and ALk always at (CA, 430ppm - ALK, 8dKh)

But now I am seeing that the CA is dropping much faster, every few days I have to do corrections, I couldnt check my CA levels for two weeks and it dropped to 341ppm, I checked MG it is fine at 1275ppm and ALk was 8pm, no signs of precipitation, I was wandering if I should raise the CA dose like 5 ml more than ALk.

[coralsnaked]

Why wouldn't you?

[downbeach]

I would check to make sure your dosing pumps are dosing the right amount. Two part solutions are designed to be used in equal parts, and given the fact that yours has been doing that up until now, I'd be suspicious of the pump not adding the correct amount.

[skidrow52]

Hi, many thanks for the reply ... I fill two containers with both solutions equally and when I refill I make sure they are on same level which tells me the pumps are doing fine, I am sure there is no issue with the pumps, the only difference I could see in the tank was that the SPS started to grow like weeds.


I would check to make sure your dosing pumps are dosing the right amount. Two part solutions are designed to be used in equal parts, and given the fact that yours has been doing that up until now, I'd be suspicious of the pump not adding the correct amount.

[skidrow52]

Whats the two part dosing designed for then?

Why wouldn't you?

[downbeach]

Hi, many thanks for the reply ... I fill two containers with both solutions equally and when I refill I make sure they are on same level which tells me the pumps are doing fine, I am sure there is no issue with the pumps, the only difference I could see in the tank was that the SPS started to grow like weeds.

Any possibility that the solution could have been made a little weaker, i.e. not enough calcium chloride?

[skidrow52]

HI ,

Well that is also not possible because I prepare 3 US gallon solution which lasts long time and this solution I re-fill in the dosing containers, there was no change in this too.

I retested MG with different test kits and they are all above 1250ppm

Any possibility that the solution could have been made a little weaker, i.e. not enough calcium chloride?

[alexander_ktn]

There is absolutely no harm in adjusting the amount of each of the two solutions to fit the needs of your individual tank, they do not have to be dosed in equal amounts.

[bertoni]

I agree that it's not required to dose the solutions in equal parts, as long the test kits are okay and the results show that it's needed. Calcium and alkalinity are consumed in a fairly fixed ratio, so generally, the 2 parts are needed in equal amounts, but pH buffers, tap water, and water changes can all change that to some degree.

[Tron_954]

well, alot of things going on here.... but yes, as SPS grow bigger, they will consume the alk and calcium much quicker... which one is depleted faster depends on your stock and corals... mine uses alk way faster lol

i would personally bump that mg a bit higher as the higher the mg, the higher you can hold the ca, so if its not holding, low mg is your main issue you would want to observe.... dosers help keep a consistency, but all 3 have to be in line...

look at it this way, you want your calcium around 425-450? then bump that mg up to 1350-1400, it will allow you to hold higher alk and calcium values in the water column....

i just figured all this out after struggling with my own 2 part dosing issues, low alk high ca, high mg, now the mg as 1380, my ca holds at 450 and alk has stabilized at 8.5....i dose 20ml of the alk and ca 2 part through 8 cycles daily via bubble magus doser...

best of luck!

[bertoni]

If the magnesium level is very low, below something like 1000 ppm, it might be a limiting factor in keep calcium and alkalinity at reasonable levels, but that's a very uncommon situation. 1275 ppm is about the canonical ocean average, and there's no need to raise that level. I ran at 1100 ppm for years without issues.

[skidrow52]

Thanks everyone for the detailed response, well I use a Salifert test kit for MG I dont know how accurate it is , anyways I have increased 100ppm of MG and manually corrected the CA levels ... I will wait 1 week and see how stable the parameters remain.

[bertoni]

Okay, that sounds like a reasonable plan to me. :)