- Location
- Hudson Yards
H guys,
I haven't been around for a while (grad school, work etc. keeps me busy) but I figured this one really was worth posting. I've had a reef tank for 10 years and this problem is a first for me.
For the past couple months I've been dealing with steadily declining pH (measured with a properly calibrated Apex controller) in a tank that's been up and running less than 2 years. Alk, Ca and Mg were all within normal limits. Water movement is more than adequate with the return and 2 Vortech 40w pumps. I tried water changes, 2 part dosing, buffers etc. and nothing helped. The pH was down to 7.7 and things were getting serious.
After all this trial and error and loss of half my SPS, I'd eliminated all causes except excess indoor atmospheric CO2. Excess CO2 combines with water molecules in the tank to form carbonic acid (CO2 + H2O=H2CO3). Accumulation of this acid relentlessly drives down down pH.
So, I ponied up and bought an indoor air quality monitor to measure CO2. Normal outside air averages around 450 ppm CO2. In my apartment with the windows closed I measured 1200 ppm - higher than the EPA considers healthy for people. With the windows open I still can't get it below 650 ppm.
In the short term I've been dosing with kalkwasser (calcium hydroxide) which combines with the excess carbonic acid to form one calcium carbonate molecule and two water molecules: Ca(OH)2 + H2CO3 = CaCO3 + 2 H2O.
I could do this long term, but it means a couple hundred bucks worth of new equipment to do it safely (i.e. kalk reactor).
Instead I'm going to try building a CO2 scrubber and hooking it up to my protein skimmer air intake. BRS sells a ready made kit and media which is essentially an RO canister containing a media cartridge filled with soda lime.
I'll be setting it up this week and will share with you my results. If it doesn't address the problem substantially enough I can always supplement with a kalk reactor.
I haven't been around for a while (grad school, work etc. keeps me busy) but I figured this one really was worth posting. I've had a reef tank for 10 years and this problem is a first for me.
For the past couple months I've been dealing with steadily declining pH (measured with a properly calibrated Apex controller) in a tank that's been up and running less than 2 years. Alk, Ca and Mg were all within normal limits. Water movement is more than adequate with the return and 2 Vortech 40w pumps. I tried water changes, 2 part dosing, buffers etc. and nothing helped. The pH was down to 7.7 and things were getting serious.
After all this trial and error and loss of half my SPS, I'd eliminated all causes except excess indoor atmospheric CO2. Excess CO2 combines with water molecules in the tank to form carbonic acid (CO2 + H2O=H2CO3). Accumulation of this acid relentlessly drives down down pH.
So, I ponied up and bought an indoor air quality monitor to measure CO2. Normal outside air averages around 450 ppm CO2. In my apartment with the windows closed I measured 1200 ppm - higher than the EPA considers healthy for people. With the windows open I still can't get it below 650 ppm.
In the short term I've been dosing with kalkwasser (calcium hydroxide) which combines with the excess carbonic acid to form one calcium carbonate molecule and two water molecules: Ca(OH)2 + H2CO3 = CaCO3 + 2 H2O.
I could do this long term, but it means a couple hundred bucks worth of new equipment to do it safely (i.e. kalk reactor).
Instead I'm going to try building a CO2 scrubber and hooking it up to my protein skimmer air intake. BRS sells a ready made kit and media which is essentially an RO canister containing a media cartridge filled with soda lime.
I'll be setting it up this week and will share with you my results. If it doesn't address the problem substantially enough I can always supplement with a kalk reactor.
