Trouble with Alk

IslandLifeReef · Aug 6, 2017

I have been slowly adding corals to a mixed reef that I started in March. I mostly have LPS which are all doing great. I also had

a birdsnest and currently have a jedi mind trick. I lost the birdsnest to RTN. I think it had to do with low nutrients. I have since fixed that problem, but my alk wants to stay in the 7.4 to 7.8 range. I have tried dosing to get it to 8.5 to 9, but it rapidly comes down to 7.9 and then slowly moves lower. I don't have to dose Cal as it seems stable between 400 and 440. I have also noticed that my sand seems to clump, which I think could be a sign of to much Alk.

Should I just let the tank settle in the 7.4 to 7.8 range where it seems to want to be or is there something else I should be doing.

All other params seem to be in range.

SG 1.025
MG 1360
NO3 1-2 ppm
PO4 .05-.1 ppm

Thanks for any suggestions.

Randy Holmes-Farley · Aug 6, 2017

What are you dosing?

There's certainly nothing wrong with alkalinity in the 7's dKH, but in general, it takes more dosing to maintain higher levels because demand rises as the alkalinity rises. That includes both demand by organisms and for abiotic precipitation.

Calcium only seems stable because it moves much ore slowly, but you are almost certainly using a balanced amount of it, and I'd suggest dosing both when you dose alkalinity. If not, you'll likely end up having to make a bigger correction to raise it.

IslandLifeReef · Aug 6, 2017

Thank you for the reply Randy.

I am using the Red Sea A and B 2 part. I am using mostly part B. I use part A when my Cal goes below 420, otherwise, I am only using part B.

So would you suggest trying to keep the ALK in the 8dKH range or reduce the dosing and let it fall to the mid 7dKH range?

Randy Holmes-Farley · Aug 6, 2017

Sand clumping happens mostly in newer systems. Perhaps because there's not as much organic matter coating the sand grains, reducing the chance for them to nucleate precipitation of calcium carbonate.

I'm not sure the difference between a tank at 7 dKH and 8 dKH is significant in terms of being optimal.