ph question

[beau758]

thanks in advance for any help. the problem is that i can't seem to keep my ph up during the day. its 8.1 to 8.4 at night. soon as the lights come on it drops to 6.7 to 6.9 no matter how much i dose (oceans blend). All my corals seem to be growing (sps and a couple of softies) good color and size, gerth. alk is 2.51 cal is 450 temp 80 tank is 120 gal. measuring with pinpoint monitors (cal and ph) salifert for alk. lighting is two 250 hq with 15k bulbs and 4 actinic t5 oh ya mag is at 1280. any thought would be apreciated. thanks

 

[DgenR8]

Have you calibrated your probe(s) lately? PH going up at night, and down in the day is backwards. Do you keep your house all closed up during the day, and open all the doors and windows at night?

 

[pdkinsel]

May sound like a dumb question, but could you have reversed your calibration fluids during calibration?

 

[beau758]

I Know it's backwards very perplexing. i have my skimmer plumed to outside air. and no reversing fluids is not a dumb question.

 

[beau758]

what about carbon or phosx reactor would that cause the problem?

 

[smpolyp]

If the pH is dropping at the prob just as the lights come on it maybe interference from the lights ballast.
If your temp of the tank increases during the day you can have a higher ox demand on the tank. In the summer it maybe best to disconect your airline from the outside as 95+ degrees is comming in contact with your tank water. Also if you do use a line outside make sure you are using a filter with carbon to help keep contaminants from the air you are pulling in.
Some of the wet ferric phosphate removers will drop the pH. The dry ferric oxide and aluminum oxide will not.
I would increase your alk to a min of 3.0 meq/L. You can dose just the alk part of the 2 part. Dose 60 mL of just alk two days in a row and check the alk again.
The good thing is the corals are fine and it is most likly something simple like an electrical interference.

 

[skinnyjoe1976]

<a href=showthread.php?s=&postid=13276576#post13276576 target=_blank>Originally posted</a> by smpolyp
If the pH is dropping at the prob just as the lights come on it maybe interference from the lights ballast.
If your temp of the tank increases during the day you can have a higher ox demand on the tank. In the summer it maybe best to disconect your airline from the outside as 95+ degrees is comming in contact with your tank water. Also if you do use a line outside make sure you are using a filter with carbon to help keep contaminants from the air you are pulling in.
Some of the wet ferric phosphate removers will drop the pH. The dry ferric oxide and aluminum oxide will not.
I would increase your alk to a min of 3.0 meq/L. You can dose just the alk part of the 2 part. Dose 60 mL of just alk two days in a row and check the alk again.
The good thing is the corals are fine and it is most likly something simple like an electrical interference.

good call on the ballast russell

 

[davy182]

I like Smpolyps point. A test kit should show a higher ph when the lights are on than what the ph meter is showing if it does turn out that their is electrical interference caused by the lighting circuit.