pH Question

[XIII]

I'm nearing the end of my initial cycle, and all of my parameters are looking really good, except my pH is lower than it should be. The last time I did a full parameter test was on Saturday, and had these results;

 

Day 15 Parameters:

Temp = 76.5 degrees F

pH = 7.95

Specific Gravity = 1.025 %ppt

kH = 9*dkH

NH₃ = 0.00 mg/l

NO₂ = ~0.5 mg/l

NO₃ = ~15 mg/l

PO₄ = ~0.5 mg/l

 

But today, my pH was down around 7.86. I used a Sera test kit and the pH probe on my ReefKeeeper Lite, and both had similar readings. All of the other parameters are within ideal or expected ranges, so I'm trying to figure out why my pH isn't balancing back up to the 8.2 range, which is where it was when I first started my cycle. Any suggestions or thoughts on this?

 

I'm expecting my first corals and clean up crew later this week, as my cycle should be complete by then, but now I'm a little worried about the pH. Advice would be greatly appreciated.

[Mr. Fosi]

7.8x isn't low for the end of the establishment cycle, nor indeed the pH at the beginning of the day before your lights come on. Finish the cycle out and do a large waterchange, give it a day and check it at the end of the light cycle before the lights go off.

[XIII]

7.8x isn't low for the end of the establishment cycle, nor indeed the pH at the beginning of the day before your lights come on. Finish the cycle out and do a large waterchange, give it a day and check it at the end of the light cycle before the lights go off.

 

So the pH decreases when the lights are off? If that is the case, this might explain it, as I have not been running my lights during the cycle period, and plan to start them on Wednesday. Why would the lights affect the pH though; just curious?

 

I plan to do a 50% water change that same day, and a final test of all parameters, including calcium and iron to have a basis for future monitoring.

 

Thank you.

[lakshwadeep]

This is a good explanation of the daily (if the lights were on) pH swing:

http://reefkeeping.com/issues/2007-05/rhf/index.php#6

[Mr. Fosi]

Probably a good link... lak is usually good like that.

 

Short answer: pH is linked to the amount of dissolved CO2 which is influenced by photosynthesis and respiration of the organisms in your system.

[XIII]

Thank you both. This helps.

[villagefrags]

Thank you both. This helps.

 

Its been a while since I have read Randy's article on pH, and I cant remember if he makes a comment regarding summer and pH.

 

One of the things that profoundluy influences pH is dissolved CO2, as stated above. In summer we tend to close the windows and run AC units. The net effect is that the other animals in the house- us, cats dogs etc, deplete the oxygen slightly, and increase the CO2 slightly.

 

You can tell if this is an issue by doing a pH test on the tank, then take some tank water in a small cup or similar outside and shake it well for a minute while exposed to teh air. Then go retest. If the level is much higher, then room ventilation may play a part in your issue.

 

Regards,

 

Paul @ teamVF

[XIII]

Its been a while since I have read Randy's article on pH, and I cant remember if he makes a comment regarding summer and pH.

 

One of the things that profoundluy influences pH is dissolved CO2, as stated above. In summer we tend to close the windows and run AC units. The net effect is that the other animals in the house- us, cats dogs etc, deplete the oxygen slightly, and increase the CO2 slightly.

 

You can tell if this is an issue by doing a pH test on the tank, then take some tank water in a small cup or similar outside and shake it well for a minute while exposed to teh air. Then go retest. If the level is much higher, then room ventilation may play a part in your issue.

 

Regards,

 

Paul @ teamVF

 

That was in the article, but thank you all the same.