pH fluctuations - should I be concerned?

InvaderJim · Apr 18, 2020

At what point should I be concerned with my pH swings? As you can see my pH swings anywhere from 7.6 at night all the way up to 8.3 at one point, which I believe was after a water change. Tank is a 13.5g Fluval Evo, everything seems to be doing ok but ideally I'd like it to be more stable. Opening a window is really only an option on a night or two a week at best due to Florida heat. Is it possible I'm overthinking this?

sarcophytonIndy · Apr 18, 2020

What is your alkalinity ? My ph never drops below 8.2, but I do have a fuge light on at night

InvaderJim · Apr 18, 2020

Alk is currently showing 8.9 with Hanna and 9.6 with Salifert. pH in the tank is currently 7.83

mitch91175 · Apr 18, 2020

InvaderJim said:
Alk is currently showing 8.9 with Hanna and 9.6 with Salifert. pH in the tank is currently 7.83

Now to decide which of those test is more close to you actual water parameters. I've had a client purchase new Hanna reagent recently that I'd say was a bad batch. Confirmed so by using a separate batch of Hanna reagent, salifert test kit, as well as an Alkatronic.

I'd trust the salifert (but that's if you have a test kit that isn't expired and you followed the directions accordingly).

mitch91175 · Apr 18, 2020

Also small tank you will have some fluctuation as you see going on. I wouldn't attempt to do anything out of the norm in such a small system.

If your tank inhabitants aren't showing any issues, I'd say leave well enough alone, but keep an eye on other parameters.

sarcophytonIndy · Apr 18, 2020

Increasing water movement could help with aeration/oxygenation, but your daily swings are not really that bad. I wouldn't worry about it.

Randy Holmes-Farley · Apr 19, 2020

InvaderJim said:
At what point should I be concerned with my pH swings? As you can see my pH swings anywhere from 7.6 at night all the way up to 8.3 at one point, which I believe was after a water change. Tank is a 13.5g Fluval Evo, everything seems to be doing ok but ideally I'd like it to be more stable. Opening a window is really only an option on a night or two a week at best due to Florida heat. Is it possible I'm overthinking this?

Opening a window will not likely do much for the pH swing except raise the whole thing (which may be a good effect, but doesn't alter the swing).

The swing itself may not be a problem, but it does have a big effect on the availability of bicarbonate to corals. I've not seen anyone attempt to disentangle pH and bicarbonate availability effects on corals.

More aeration will reduce or eliminate the pH swing.

An additional concern is that such a large swing and the follow on interpretation that aeration is not that high is that O2 at night may get too low.

Do you have a skimmer? A closed sump where you could add an airstone?

InvaderJim · Apr 19, 2020

The tank is an AIO, so unfortunately no skimmer or sump. I have considered putting an air stone in the first camber but I’d be concerned about micro bubbles making it back into the display. I recently upgraded the return pump and added a random flow nozzle so maybe increased water movement will help?

My main concern is the pH dropping below 7.7 at night which I’ve read can cause skeleton dissolution.

Dom · Apr 19, 2020

InvaderJim said:
At what point should I be concerned with my pH swings? As you can see my pH swings anywhere from 7.6 at night all the way up to 8.3 at one point, which I believe was after a water change. Tank is a 13.5g Fluval Evo, everything seems to be doing ok but ideally I'd like it to be more stable. Opening a window is really only an option on a night or two a week at best due to Florida heat. Is it possible I'm overthinking this?

Wow... that does seem like a pretty big swing...

Please explain this chart to me.... Is that 12:00 midnight or 12 noon?

I believe pH fluctuates with the light cycle, doesn't it? Peaks with lights on and goes down with lights off.

This is why we run refugium lights opposite the light cycle.

Randy Holmes-Farley · Apr 20, 2020

InvaderJim said:
The tank is an AIO, so unfortunately no skimmer or sump. I have considered putting an air stone in the first camber but I’d be concerned about micro bubbles making it back into the display. I recently upgraded the return pump and added a random flow nozzle so maybe increased water movement will help?

My main concern is the pH dropping below 7.7 at night which I’ve read can cause skeleton dissolution.

I understand the concern over pH 7.7, but I think O2 may be an equally important concern.

InvaderJim · Apr 20, 2020

Dom said:
Wow... that does seem like a pretty big swing...

Please explain this chart to me.... Is that 12:00 midnight or 12 noon?

I believe pH fluctuates with the light cycle, doesn't it? Peaks with lights on and goes down with lights off.

This is why we run refugium lights opposite the light cycle.

On the The Apex graph the 12 is 12pm and the date is 12am. The pH does dip and raise with the light cycle. Last night it went from 8.2 to 7.69 this morning with the lights off.

Randy Holmes-Farley said:
I understand the concern over pH 7.7, but I think O2 may be an equally important concern.

Other than increasing water movement how would you remedy the O2 being low? I have quite a bit of surface agitation. Much more than before I upgraded the return pump and the problem still persists. Would lowering the water level in the rear chambers so that there is drop off help? On the plus side my fish aren’t showing any signs of lack of oxygen yet.