explosive alk consumption?

htownguy · Mar 22, 2018

Hi everyone. I have a question about my recent alk consumption. So around a week and a half ago I added a 300w LED light to my fuge. This has made my cheato explode and has kept my PH in the higher range. So before the new light my ph would range from 7.9 to 8.3. Now it ranges 8.3 to 8.5 steady for the last few weeks according to my apex. In this week and a half I have had to dose 8ml more of alk and cal and still going. The growth and colors seem to be the same which is great. just curious if a higher ph would be the reason for this. little tank info. 70 gal cube. sps dominate. haven't changed anything else. Use a Hanna checker with 2 different reagents. Id say within the last year ive had to raise my dosing maybe 12ml. I guess its a good thing right?

rkpetersen · Mar 22, 2018

Basically, yes. Higher average pH = More active deposition of skeletal calcium carbonate by growing stony corals = Increased alk consumption. All good. Although increased pH itself also results in lower measured alk levels (by a mechanism that I personally don't fully understand), independent of coral growth, so don't push your dosing too hard to get to some magic number, if your corals are doing well.

Fourstars · Mar 22, 2018

It's a good thing! Here's a link that will help you understand the relationships between the three.

http://reefkeeping.com/issues/2005-03/rhf/

htownguy · Mar 22, 2018

Thanks for that article. I remember reading that years ago but totally had forgotten about it. I am just trying to keep a steady 8 dkh. It has been dropping steadily into the low 7s and a 6.9 reading today. according to that article my ph might be to high right now in the 8.5 range? I haven't seen any precipitation on pumps or heaters anywhere. I might cut back slightly on my refugium light schedule.

Randy Holmes-Farley · Mar 22, 2018

Higher pH will also accelerate abiotic precipitation of calcium carbonate (as on heaters, pumps, sand, etc.), increasing demand. You do not always see it. :)