Need advise: Low pH around the board

[luckycat]

Hello,
I've had my 90g setup for about 4-5 months; pH has been typically a bit low - around 8.0 or so... it is now, however, 7.4, the lowest measurable value in my test kit. I also tested my tap water (just a shade darker than 7.4 but I'd still put it in that category), RO water (7.4). I use IO for my salt mix, no additives.

My other params are S:1.022, 0 Ammonia, 0 Nitrates, 0 Nitrites. I have experienced nuisance hair algae in the display tank that I'm trying to get rid of by pulling/siphoning, and I have a fuge in the basement w/chaeto that is growing very nicely (I need to trim now once a week or so).

Tanke is bb - well - epoxy/sand mix - and fuge has 5" dsb.

I'm freaking out about this low pH... I've read that this can be caused by lack of gas exchange - I have a canopy top but no glass on top of the tank, water goes down to the basement for my sump/fuge, hob air skimmer (css), and water moves from display downstairs through pvc which goes through mechanical filtration - with all of this movement I thought I'd be getting good gas exchange.

One other thing - I have a green star polyp that was put in the tank about 2 months ago - it has been thriving, seemingly, until just recently - hasn't come out in about 2-3 days. I'm wondering if this is related to the low pH? All fish and shrimp seem to be fine.

BTW I'm getting alk and ca test kits today. I'm also going to get a separate pH kit, maybe a monitor, to validate my pH readings.

I have kalkwasser mix that I might be able to use as well...

 

[Hara]

I notice that you live in michigan, I am sure it is pretty cold there now. The reason I mention this is believe it or not, if the air is "stale" in your house, even though you think the gas exchange is there, it isnt effective. I had this same problem during the summer when the house was closed up due to air conditioning. After a few days o airing the house in the cooler nighttime temps, the ph came back up. I would also add powerheads at the surface of the tank to toss some water about.

 

[luckycat]

I notice that you live in michigan, I am sure it is pretty cold there now. The reason I mention this is believe it or not, if the air is "stale" in your house, even though you think the gas exchange is there, it isnt effective. I had this same problem during the summer when the house was closed up due to air conditioning. After a few days o airing the house in the cooler nighttime temps, the ph came back up. I would also add powerheads at the surface of the tank to toss some water about.

Yes excellent observation. It has been in fact cold.. for the past few weeks temp has been dropping, less fresh air in the house definately. This does seem to coincide with drop in pH in all of my water sources. As I mentioned when I measured it last it was 8.2 or thereabouts a few weeks ago - when it was not nearly as cold.

The basement sump is in a 16x20 room (approx) that houses our furnace as well.

I have a spare power head that I'll put near the top of the tank to agigate the surface some more and see what that does to pH.

Thanks for the feedback!

 

[saltwatersmac]

I also have seen where people have run their air intake on the skimmer somewhere to receive fresh air.

 

[HoopsGuru]

I would take a bucket of tankwater outside in the fresh air and run a powerhead/airstone and heater on it. This is a quicker way to see if O2 is the problem as 7.4 is probably stressful right now to all of your livestock.

 

[luckycat]

Amazing pH - is 0.6 fluctuation in 24 hrs possible?

Well, I have no idea what is going on here...I think 100% user error.

I purchased another pH test kit, to confirm that my current kit is working... getting pH of 8.1 (somewhere between 8.0 and 8.2).. in my RO water, salt mix (fresh) and tank! And I tested with my current kit again, and got solid 8.0 readings from all sources!

What in the world? Could pH naturally fluctuate from 7.4 to 8.0 in the course of a day? I really haven't done anything...and I'm pretty sure I didn't screw up the tests, since I did 4 in a row and I've been using this test kit for about a year. Is it possible that pH could have fluctuated by itself like that in 24 hours, or am I thinking I screwed up something 4x when I was testing?

 

[HoopsGuru]

An important thing is to test at the same time of day, the PH will drop overnight (unless dripping kalk, running a reverse photoperiod on a refugium, etc.) and not peak again until well into the light cycle. That is a fairly large swing, but I have seen it before. CO2 builds up overnight, and if you already are having an oxygen exchange or low local oxygen level problem it could be simply making a normally small swing a larger issue.

 

[luckycat]

Interesting...well when I measured pH last time and got the very low readings it was late at night, probably 11 PM or so. When I measured today it was around 1 PM. I have added a ph at the top of the tank to make sure the surface is being agitated..I'll take readings for the next few days at roughly the same time to see where my pH is heading.

Oh btw, I am, however, running reverse photoperiod on my fuge, which contains a lot of chaeto... in theory that was supposed to even out pH. I have no idea what happened...

 

[HoopsGuru]

Hmmmm.....definitely test again tomorrow and let us know what your readings are on both kits. My hunch is that it might have just been a glitch and that things are actually fine. As far as your star polyps are concerned, it is normal for them to close up for a few days from time to time, you can blow them off a bit with turkey baster if you want to make sure there is no detritus settled on them which is annoying them.

 

[luckycat]

Hi - well tested again this morning (9:10 am) and the display tank (well, measured from fuge) is 8.2! So maybe it was just a glitch...polyps have not come out again, though, except for a small section of it...

I'll blow off the polyp today a bit when I'm doing my weekly tank clean-up/H2O change.