Big alk consumption from FOWLR

[Crazed]

Hey guys,

I'm just polling for thoughts. In recent months I've been dosing with Randy's two-part #1 recipe. I didn't get serious about it until a couple weeks ago. For five days I dosed 17mL/day for my 70 gallon tank with 20 gallon sump (I figure there's about 78 gallons total water volume in there). When I started, alk was 9 dKH and calcium was about 460ppm. After those 5 days, my alk still decreased from 9 dKH to 8 dKH. The calcium was down to 440ppm. So, after some calculations, assuming those numbers remain constant, I figured that it would take about an additional 11mL/day to maintain the alk level, for a total of 28mL/day.

This seems a bit much to me. The only things in the tank using calcium carbonate are coralline algae and, like, two snails. There's a lot of coralline algae, and while I love it, I don't even have any corals in there yet! I don't want all of my alk to be eaten up by coralline algae, leaving my future corals to "starve".

Do these numbers make sense? If I keep upping the dosage, doesn't that mean the coralline algae would proliferate proportionally, demanding more calcium carbonate? How are the corals going to be able to use it for their skeletons? I feel like I'm dumping quite a bit in there already even when I have no corals, so I can't imagine what it'll be like when I do finally get some.

If this seems okay, I'll certainly raise the dosage, but I just want to make sure it's plausible.

Thanks. :)

[bertoni]

Those numbers seem reasonable to me. The amount of coralline will grow to cover all the appropriate surface available, which could increase the total consumption rate. The corals will be able to compete well enough, so long as the dosing keeps up with demand. I'd just increase the dose.

[Crazed]

Thanks!

[bertoni]

You're welcome! Good luck!

[iamwrasseman]

your bioload may be depleting the alk ,how many fish do you have in the tank ? you also may be overfeeding the tank and that could be your problem .

[Billybeau1]

I'm not sure what overfeeding may do for increased alkalinity consumption, but my fish only certainly consumes much more alk than calcium.

Like Bertoni said, I would just up the alkalinity dosage to maintain your target.

[Chris27]

Don't be fooled, coraline may not have branches or polyps, but it can suck the dickens out of some supplements. In addition to your dosing / testing, run a test for magnesium, I would bet you measure about 1100 if you haven't been dosing. A low mag concentration makes it difficult to maintain calcium / alk.

[bertoni]

I'm not sure what is meant by "bioload depleting alkalinity", but the only way alkalinity can be removed in any significant amount due to bioload would be water changes in a high-nitrate tank, as far as I can remember right now. This article goes into details:

http://reefkeeping.com/issues/2004-12/rhf/index.htm

I should take a look, since it's been a while since I've been over it.