PH and ALK issues

aileen · Feb 4, 2018

So, I've been struggling with very low alk and calcium levels. I've kept my ph up above 8 consistently using a Co2 scrubber on my skimmer. I've been dosing stupid amounts of alk and calcium BRS 2 part the last month (like maybe 100 ml or more a day with 170g total water volume) and have been nothing but frustrated about my low alk (around 6) and low calcium (around 400 or less). Well, today I calibrated my Neptune Apex double junction ph probe and when I was done the ph shot up to like 8.5 and stayed there consistently for 20 min or more leading me to believe the ph has been way higher in my tank than I believed. So this is my theory and tell me if I'm wrong:

I noticed while cleaning up my sump today that there was massive amounts of precipitate on my heaters, return pump, skimmer and probes, etc. I'm guessing my ph was really more like 8.6ish and above due to my ph probe being out of calibration. So with ph that high, my dosing was doing nothing more than precipitating all over my equipment. I am right to believe that high ph (8.5 and above) will cause the brs 2 part solution (soda ash and calcium chloride) to simply precipitate and not raise the alk and calcium levels?

I've since performed a 40g water change and taken off my C02 scrubber to bring my ph down to around 8ish with my freshly calibrated probe. I'm thinking that I may finally get my alk to around a steady 7 and my calcium to a steady 450 with the lower ph since my dosing will not result in constant precipitate? Wrong?

jsker · Feb 4, 2018

What tests are you using for alk and Ca?

How old is the system?

aileen · Feb 4, 2018

Hanna for alkalinity and Sailfert for calcium. The system is about 3-4 months old. And just for giggles, I was so confused I've actually been testing twice because I thought I was screwing up and getting bad readings, but I really don't think that has been the case despite my lame ph probe maintenance....lol

Randy Holmes-Farley · Feb 4, 2018

I’m curious why you think the dose is excessive. It is only 0.8 dKH per day.

That said, both consumption by corals and abiotic precipitation rise as pH rises, and letting the pH fall back will likely allow the alk and calcium to rise given the same daily dose ( or a lower dose). [emoji3]

aileen · Feb 4, 2018

Well, I'm thinking the dosing is excessive because the tank itself is only 80g and the sump is a 150g rubbermaid (maybe 170 total water volume). The tank is not that large. I have maybe 5 chalices, 2 diff acans, a torch, a lobo and 10 smaller sps frags. It seems really a lot to me. My old 200g setup with a 100g rubbermaid sump managed to survive on kalk alone although the evaporation rate was high and I had massive sps colonies. This system has a lower evaporation rate compared to my old system (we are in a new home now). Maybe I'm being presumptuous...every system is different I know, but the chemistry of it just doesn't seem to add up. Also, I believe the dosing was also excessive because of the large amount of hardened precipitate on the equipment. Mind you, I came here for advice since I'm no chemist...