Slightly unbalanced Alk & Cal dosing?

R6REEFER · Feb 23, 2016

Hey reefers, in particular Randy,

Not sure if you remember our discussion on my low ph and Sodium carbonate dosing but I've made some purchases and adjustments. My problem was that I had naturally low ph in this apartment which I supplemented with 19 grams of Na2CO3 per 5 gallon ATO. That solved the ph and alk crisis but I was still unveiling abnormally low calcium levels for a fairly new tank. I purchased the necessary chemicals and started experimenting. What I landed on was the following:

30ml per day of Cacl2 raised levels from 360 ppm to 420 ppm over the course of a week along with the initial dose of 400 ml to adjust.

25ml per day of Na2CO3 via 5 gallon ATO to balance alk out to 10.6 dk/h.

Ph is sitting right at 8.1 with no additional additives.

My question is will the unbalance of 5 ml between the 2 additives have a substantial effect on my tank in the long run? I know equivalent levels of each should be dosed by rule of thumb but if I raise the Na2CO3 dose to 30ml per day I get an unwanted alk level of 11.4 dk/h. If I drop cacl2 to 25 ml per day it drops my calcium to 400-410 ppm which is a bit too low for what I'm trying to achieve.

Can I continue to dose 25ml of Na2CO3 and 30ml of cacl2??

Thanks in advance!

Randy Holmes-Farley · Feb 24, 2016

Yes, that is fine.

If the need for unbalanced additions is real (say, because of water changes with a mix that does not match the tank) or for other real reasons (such as rising or falling nitrate levels, which impacts alkalinity), or because the solutions do not exactly match, it is fine to dose unequal amounts.

That said, because calcium moves so slowly, and because testing has uncertainty associated with it, it may require a long period of actual dosing to know exactly what ratio is required to perfectly balance the consumption.

R6REEFER · Feb 24, 2016

Randy Holmes-Farley said:
Yes, that is fine.

If the need for unbalanced additions is real (say, because of water changes with a mix that does not match the tank) or for other real reasons (such as rising or falling nitrate levels, which impacts alkalinity), or because the solutions do not exactly match, it is fine to dose unequal amounts.

That said, because calcium moves so slowly, and because testing has uncertainty associated with it, it may require a long period of actual dosing to know exactly what ratio is required to perfectly balance the consumption.

Okay, glad to hear it. Nitrates have been steady hovering around 8. I will continue to monitor daily until I got it dialed in perfect. Thanks Randy!