alk issues

[grasshopper]

I know this is a low-level chem. question, but could someone please tell me what consumes Alk.?

I am having troubles keeping my Alk. up. My Ca always tests at 450. My Alk. usually goes down to 8.3 - 8.7.??

I always use the baking soda mix to bring it back up to 10 - 11. Then a few weeks later it has dropped again. The only thing I dose if B-ionic 5 teaspoons a week. I always put the same amount of both parts in, and I always shake the bottles first.

Some other things to note about my tank - it's TWV(total water volume) is 100 gal.s I have mainly LPS some softies and some SPS. I have a medium to heavy bioload. I have an slightly elevated Nitrate level that I've battling since my fuge died off a few months ago. It was at 100ppm, now it's down to 10-20 ppm. I have a hair algae outbreak due to the trates - at least that's what I think it's due to.

I've re-established my fuge, and have lots of macro algae in it. I'm hand pruning the hair algae, and have read that higher Alk. levels help in keeping hair algae at bay.

I hope some of this can be tied to my dropping Alk., but I can't figure out how.

Anyone??

TIA
GH

[Randy Holmes-Farley]

I know this is a low-level chem. question, but could someone please tell me what consumes Alk.?

Generally, it is calcification, either by corals and coralline algae, or abiotic precipitation on heaters and such.

Other processes are more minor, but certain metabolic processes can reduce alkalinity. For example, having the nitrogen cycle proceed to nitrate and stop there.

However, when you are not adding enough of a balanced calcium and alkalinity additive, you notice the effects on alkalinity first, because there is a larger reservoir of calcium in seawater than there is alkalinity.

So my suggestion is that if you want to keep alkalinity higher, then you should add more of both parts of the B-ionic.

[grasshopper]

So even though I'm registering enough Ca for my tank, what you're saying is that if I added more of both parts B-ionic, then it would raise my alk??

Wouldn't that also raise my Ca? where would the extra Ca go? Would it precipitate out, or would the reef inhabitants consume it??

Just as I think I get my head around things - I always feel like I go back to square one:P

Thanks Randy

[Randy Holmes-Farley]

So even though I'm registering enough Ca for my tank, what you're saying is that if I added more of both parts B-ionic, then it would raise my alk??


Yes

Wouldn't that also raise my Ca? where would the extra Ca go? Would it precipitate out, or would the reef inhabitants consume it??

Even if nothing happened to it, it won't rise much. Adding a balanced additive adds only 20 ppm calcium for every 1 meq/L (2.8 dKH) of alkalinity.

So if you are at 450 ppm Ca++ and 8 dKH, then you can use both parts equally and get to 460 ppm calcium and 9.4 dKH.

[grasshopper]

Excellent thanks as always Randy!

[Randy Holmes-Farley]

You're welcome.

Happy reefing. :)