Two Part Dosing

[stoj]

I use b-ionic two part to maintain my Alk and Ca levels in the tank. For Mg I use b-ionic also. I am using Aquaforest Probiotic salt to do water changes and the levels in the bucket are:

Mg 1350
Alk 7.5
Ca 410

These levels are stated on the certificate inside of the bucket and I received the same results with Salifert tests.

My water parameters are as follows:

Mg 1350
Alk 8.2
Cal 435
NO3 2
PO4 <0.03
Salinity 1.024

I use a refractometer that was calibrated with 35 ppt solution and Salifert test kits for all other parameters.

The trouble that I am having is that I am not dosing two part as 1:1 ratio as it is supposed to be dosed. As of right now my Ca consumption is 27 mL, Alk consumption is 5 mL a day, Mg consumption is at 30 mL. These are dosed daily via dosing pump that I set up to dose 6 times in 24 hours. I have a 125 gallon mixed reef with many sps frags. I test everyday just to make sure my pump doses correctly and adjust dosages accordingly if necessary. I am curious as to why I cannot dose two part in equal amounts? Should I raise my salinity to 1.026? I also have been running biopellets for about 1 1/2 months and I am trying to slowly bring down Alk to 7.5 dKh.

Thank you

[thegrun]

Off topic but I would raise the salinity closer to natural sea water 1.026. The problem (if it is one) may well be with your dosers delivering different amounts of solution. You can test the dosing pumps by running them for say 10 minutes dumping the solution into a gradated beaker to measure the results. I know my BRS dosers all deliver different amounts of solution. It should also be noted that not all corals will use the exact 1:1 ratio of alkalinity and calcium, so that will play into the equation. Are you seeing any signs of calcium precipitation either in the form of sand clumping or a thin calcium deposit on the sides of the tank? If not I really wouldn't worry about the differences although yours is extreme.

[stoj]

Before I installed the dosing pump unit, I calibrated each dosing pump to pump 100 mL of RODI water into a 150 mL beaker. After the doser was calibrated, I checked if it would dose the same amount that it was calibrated for and everything checked out. I was using the same beaker to dose daily by hand.

[bertoni]

I agree with raising the SG to 1.026. The consumption ratio you give seems strange. Are you using a pH buffer? Or tap water? pH buffers all add alkalinity, and tap water can have a fair amount, too. How long have you been dosing this way? It'd take a long time to make a noticeable change in the calcium and magnesium levels with that dosing rate.

[stoj]

I will be topping off with saltwater for now to raise salinity to the correct level. I have a rodi unit from brs and change filters on it every 6 months although I don't have to. I am also not using a buffer and I have been dosing by hand everyday before the dosing pump. I had all the numbers figured out prior to using the doser. Before I cleaned the tank from all the coralline algae I was dosing the tank by hand as follows:

Mg 23 mL a day
Alk 30 mL a day
Ca 30 mL a day

[bertoni]

Well, as long as the params stay at acceptable levels, I wouldn't worry about the dosing rates all that much. Ignoring water changes, I would expect that the calcium supplement should be raising that parameter by about 100 ppm per month, but it's hard to know exactly what is happening.