pH concerns

w.gurney77 · Dec 28, 2014

I have concerns about my pH dropping to 7.7. This is a fairly new system and the first time I have an apex controller. I have read not to chase pH, but 7.7 seems a bit low to me. The only thing I did yesterday was clean the glass.
Total system volume is about 140 gal with the displacement. 93 gal display, 30 gal frag tank, 20 gal refugium and the sump runs with 15 gal.

My pH has been staying between 7.8 and 8 which is fine. I would like it to range from 8.1 to 8.3. This system has been up for about 2 months. I have a light bio load and my parameters are as follows:
Alk 9.8
Cal 480
Mag 1340
PO4 .03 or less
NO3 .5 or less
pH has come up to 7.84 today

I am waiting for my calcium and mag to drop a little. I dose manually and don't have enough hard corals to start up my calcium reactor.I have one tester acro I put in last week. It is encrusting, the polyp extension is OK but not great. I have about 20 pounds of live rock and the rest was dry rock.

Is it possible to raise pH without raising alk? I'm not sure because pH is directly related to calcium carbonate and CO2.

Is this low pH a problem? Will it correct itself? Is this normal with a new system?

This is my first ( soon to be )SPS tank. I have had other tanks, but never really monitored the parameters closely.

Randy Holmes-Farley · Dec 28, 2014

There is nothing to add to boost pH without boosting alkalinity, but reducing the CO2 in your home air can raise pH, as can adding a high pH additive when you do need alkalinity.

w.gurney77 · Dec 28, 2014

Thanks Randy! I add lime water when my alk drops to 9. With the light bio load it takes a few days. Should I just add more stony corals to increase the alk draw? I was waiting for the system to age a bit.

I had the windows and doors on the cabinet open today. I will leave them open tonight to see if it helps.

Cory · Dec 29, 2014

You gotta open the windows and doors in your house not the cabiniet to effect Co2 and subsequent ph. If you had enough corals to consume alkalinity and calcium then you could add more limewater that would keep your ph high. Some people report success running their air intake of the skimmer outside to raise ph.

w.gurney77 · Dec 29, 2014

I had the windows open for a while last night. The pH continued to rise even after lights out on the tank. It is now at 7.88. Should come up even more when the lights come on. Guess I didn't realize how much CO2 could build up in the house.

beaslbob · Dec 29, 2014

My ph rose once I balanced out the tank with macro algaes.
the highest pre macro pH was much lower then the lowest post macro pH.
my .02

UK_Pete · Dec 29, 2014

My pH went from 7.9 to 8.4 when I ran the skimmer air intake outside, but I currently have a very low bioload for my 55 gallon tank (1 smallish fish). Most people seem to report 0.2 pH increase from doing this in more heavily loaded systems. The effect will probably depend on how much CO2 you have in your room, with several kids running round all day in my tank room, and with 0 degree C temps outside, my windows and doors are shut tight and so my CO2 seems to rise very high judging from the pH improvement when I changed to outside air on the skimmer. The pH is directly related to the CO2 in the tank for a specific alk as detailed in one of Randys articles, with graph provided, and your tank CO2 is going to be strongly affected by your room CO2 unless you use outside air for your skimmer (ie the tank has to use the room air to get rid of its CO2 during the night and day also unless you have significant nutrients and plenty of algae, so high room CO2 means tank CO2 can't fall below that room CO2 level).

w.gurney77 · Jan 24, 2015

With the windows open for a while my pH now stays between 8.1 and 8.3.

lionfish5740 · Jan 24, 2015

Fresh air makes a huge difference! At the worst of times in the past, my system ran to 7.56 at the lowest during lights out and my corals were fine. Just imagine how many years you and other people had successful tanks without the constant monitoring of pH! Just worry about your Alk level and use your pH to spot large swings in Alk.

BTW, that low pH I talked about above was from poor aeration and carbon dosing during the hours that it was lower anyway. I corrected mine at the time by spreading the carbon dosing out in smaller doses throughout the day when the lights were on. Thought I would add that just in case it helps anybody.

Randy Holmes-Farley · Jan 26, 2015

w.gurney77 said:
With the windows open for a while my pH now stays between 8.1 and 8.3.

Glad that helped!

Happy Reefing.

Randy Holmes-Farley · Jan 26, 2015

lionfish5740 said:
Fresh air makes a huge difference! At the worst of times in the past, my system ran to 7.56 at the lowest during lights out and my corals were fine. Just imagine how many years you and other people had successful tanks without the constant monitoring of pH! Just worry about your Alk level and use your pH to spot large swings in Alk.
.

Maybe.

Or imagine how much better the corals might have been is the pH were higher.

w.gurney77 · Jan 26, 2015

I check my alk twice a day to avoid large swings. I then dose according to test results. Alk draw is about .2 dKH per day if I let it drop that much. I only have about 12 small frags so I still manually dose twice a day.