pH help

[Gordo]

I need a little assistance with my pH. Over the last several months my pH had been creeping up 8.4...8.5...8.6... Okay time to check my monitor. I calibrated with the 7.0 and 10.0 solution and got it to read in each solution within +-.03. I figure cool probe must still be good (it's about 18 months old). I stuck the probe back in my tank and it read 7.9 - 8.0. So I'm thinking my water has gotten out of whack and I do a 30% water change. This doesn't make the pH budge, still 8.0. So I test with the Salifert kit just to confirm my equipment is good and it reads ~8.0 as well. I've been using the same bucket of salt for the last 9 months so I don't think that's it. The one thing I didn't do is test my makeup water to see what the pH of that is. I'm mixing up 5 gallon right now to see what the pH on that is. What could be going on to cause my pH to be out of whack?

Tank Specs

72G tank with ~30G sump/refug.
Mixed reef
Water changes every 6-8 weeks
No additives being added on a regular basis

Thanks,

Gordo

 

[reedman]

You could try the aeration test on a sample with outside air to see if you have elevated CO2 levels in your house.

Also, where's your alk at? When my alk was low my PH dropped with it.

just a couple of thoughts.
-Reed

 

[Katchupoy]

Gordo. How often do you clean your probe? How about bubbles getting stuck on the probe?

I have a question also if I may Gordo. I just bough PH monitor last week. Calibrated it and used it. My lowest is 7.9 at around 4:00am (early morning) and 8.7 around 4:00 pm.

Is this alright? Dont havee any idea what so ever. I know that it should be 8.3 or something.

Thank you.

 

[jasontatro]

Yikes!!! A swing of .8 in a 12 hour period. That can't be good. Sounds like you need to do something to stabilize that pH overnight.

 

[cwcross]

You could try the aeration test on a sample with outside air to see if you have elevated CO2 levels in your house.

Also, where's your alk at? When my alk was low my PH dropped with it.

just a couple of thoughts.
-Reed

I second that...where is your ALK at?

 

[Gordo]

I'll test that tonight.

 

[Angelscrx]

Gordo. How often do you clean your probe? How about bubbles getting stuck on the probe?

I have a question also if I may Gordo. I just bough PH monitor last week. Calibrated it and used it. My lowest is 7.9 at around 4:00am (early morning) and 8.7 around 4:00 pm.

Is this alright? Dont havee any idea what so ever. I know that it should be 8.3 or something.

Thank you.

I have a refugium that the lights stay on while the lights in the mian tank are off. This helps maintain PH at all times if I am not mistaken? It also keeps the cheato and cualerpa in check.