ph dropped to 8.0

[kimberly]

My husband has a 92 gal reef tank. It is about 10 w/o. I ran the tests for him today and found that the ph was around 8.0. It used to be 8.4. (The last time I ran the tests was probably about 2 w ago...yes, I know that the tests should be run more often, but it is *supposed* to be husband's job, not mine.) I don't know what happened. I actually ran ph twice to be sure I didn't make a mistake. We recently switched to using r/o water for water changes and top offs, could this be the problem? How do we fix it?

all the test results:
ammonia: close to 0, but slightly registering something
nitrate: high range 100
nitrite: 0
ph: 8.0
alk: high normal
salinity: 1.023 (needs to be topped off which will lower this back to its normal 1.022, but I want to hold off until we find out about the ph)

Thanks,
Kimberly

Originally Posted by kimberly

I ran the tests for him today and found that the ph was around 8.0. It used to be 8.4.

Given the time of day this post was made, I'm wondering if you also just tested the pH? Lower pH values in the early AM, especially just before or after the lights come on is perfectly normal.

Cheers
Steve

[Oceanicsublimat]

I've read that the photosynthesis in plants and other algae raises the ph.. that's why in the morning the ph is typically lower than evening..I've not really worried about my ph...

[kimberly]

Would testing first thing in the am before the lights have been on for long make a .4 difference in the ph? I can test again later when the lights have been on for quite a while, I usually do run the tests in the late evening.

Thanks, I will update later in the day when I test ph again.
Kimberly

[Hara]

it will make a substantial difference.

[kimberly]

I tested again around 5:30 and it was still 8.0. The lights had been on for hours by that time. I can test again in a few hours, but it doesn't seem that it is going to go up. What do we do?

Kimberly

[quarryshark]

8.0 is not really low, its at the low end of the good range.
How long has the tank been set up? Do you have a glass cover? Glass covers can impede gas exchange and cause the ph to drop.
Take a bit of tank water, put it in a container, airate it for a few hours and test that water. That will tell you if there is sufficient exchange in the system.

[kimberly]

It has been set up about 10 weeks. It has a glass top. I will try your suggestion about putting some water out and testing it.

Thanks.
Kimberly

[quarryshark]

If the PH rises in the container, then you may want to consider removing at least part of the glass top and replacing it with some eggcrate. Also, if you have any PH's in the tank, you may want to point one or two towards the surface. Surface adgitation is needed for proper gas exchange.

[kimberly]

Right before the lights went out I tested ph again and it went up to 8.2.

The surface agitation may have been the cause. I didn't know that. But we had a power outage the other day and husband moved the powerhead to keep the water from draining out to the sump (I think that was the reason, you guys would know better than I, he just said that he better move it quick). When the power came back on he adjusted the powerhead, but it was obviously different than it was before.

Thanks again for the help!
Kimberly

[quarryshark]

Glad you found the cause.