Two part dosing advice

[apex003]

Wondering what I should do here. I'm dosing B-ionic two part and my Alk is at 11.5 but CA is only at 370. Alk stays stable, but CA seems to gradually decrease between water changes every 2 weeks. I'm dosing both in equal parts at the moment. My reef crystals mix out of the bucket is 12.5 Alk and 430 CA.

It seems like CA consumption is outstripping Alk, but I don't want to bump up dosing of both parts and drive Alk any higher. I'd prefer CA closer to 420, and Alk at 10.5

Should I:
- Keep dosing in equal parts at current levels and accept CA lower than I'd want?
- Bump up CA only and break the 1:1 ratio of each part?
- Bump up both and let ALK go higher?
- Dose a separate CA supplement to keep CA on target? If so, what supplement do you recommend that's purely CA?
- Something else?

Thanks!

 

[Randy Holmes-Farley Verified Community Expert]

I'd make a one time correction of calcium to 430 ppm over a couple of days with 2-3 manual doses, then switch to a slightly higher doser dose of calcium dose per day (say, 20% higher), tweaking that if calcium starts to get higher or lower than you want.

You can use just the calcium part of B-ionic, or you can buy some calcium chloride for that purpose (which is cheaper and not any problem to use for corrections).

 

[Reab]

theres no harm in breaking the 1:1 ratio. all it tells me is the salt you are using is low in calcium and/or your corals are using it like crazy. I personally would just up the 2nd half of the b-ionic so im not introducing yet another variable into the tank.

 

[Randy Holmes-Farley Verified Community Expert]

In addition to salt mix issues, some aspects of the nitrogen cycle can consume alkalinity, so how you deal with nitrate can impact dosing of alkalinity.

Specifically, if you are allowing nitrate to rise, alk will be depleted.

Also, if you use a sulfur denitrator, that will consume significant alkalinity.

This has more:

When Do Calcium and Alkalinity Demand Not Exactly Balance? by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2004-12/rhf/index.htm

 

[apex003]

Thanks Randy and reab! I think I'll make the adjustment per your advice Randy over the next couple days.

You raise a relevant question about the nitrogen cycle. I just started dosing stump remover last week after determining that I think the system is nitrogen deficient. Perhaps that's why I'm seeing what looks like slower Alk consumption.

Based in this, I'm thinking of doing the one time correction, but holding on changing the doser until I see if the nitrate dosing has an impact.

I'll just up my testing to see if / how fast the CA and Alk get mismatched again.

 

[Randy Holmes-Farley Verified Community Expert]

Dosing nitrate and having it incorporated into organisms will tend to boost alkalinity, although the effect is not huge.

A 2 ppm boost to nitrate, and then having it consumed will result in a boost of about 0.09 dKH of alkalinity.

But if you did that every day for a week, it will add up (0.6 dKH).