High pH

[rock_lobster]

I've been dealing with pH spiking up to 8.5 every evening and dropping to 8.1 at nights. Its been like this for a few months now since I started feeding more heavily. I am assuming that the chaeto is using up all the CO2 to take care of the nitrates and phosphates which are not detectable even with an excessive amount of feeding. Whats the best way to keep the pH below 8.3 without decreasing feedings assuming that is the problem. I am dosing soda ash as well and would like to keep using that because it took me so long to dial it in just right on the doser.

 

[Willz]

I have had good success running my refugium lights on a counter-cycle to my tank lights. So, when the tank is lit the refugium isn't and vice versa.

 

[rock_lobster]

I have had good success running my refugium lights on a counter-cycle to my tank lights. So, when the tank is lit the refugium isn't and vice versa.

Yep I have that setup already.

 

[Willz]

Yep I have that setup already.

OK. Just checking :) I'm eager to hear what other people do, too. Following.

 

[Randy Holmes-Farley]

pH 8.5 is no concern and nothing needs to be done. It is better, probably, than pH 8.0. :)

Aeration will reduce or prevent the daily pH swing if you want to, but it is not needed for this reason.

 

[Randy Holmes-Farley]

I discuss high pH here:

High pH: Causes and Cures by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2005-03/rhf/index.htm

 

[Downbeach]

What are you using to measure it with? If a meter/controller, when was the last time it was calibrated? How old is the probe?

 

[joaocdestro]

This is just an idea: If you add the sodium bicarbonate (alk solution) on the evening to reduce the ph and let the skimmer aerate it will increase the ph on the morning?

 

[Randy Holmes-Farley]

This is just an idea: If you add the sodium bicarbonate (alk solution) on the evening to reduce the ph and let the skimmer aerate it will increase the ph on the morning?

Sodium bicarbonate has a slight pH lowering effect when first added. Sodium carbonate has a substantial pH raisiong effect. Limewater (kalkwasser) has an even bigger pH raising effect per unit of alk added.

If you fully aerate the water after the addition, they all come to the same pH if you are at the same tank alk value.

It is theoretically provable, but I also showed it experimentally here:

Chemistry And The Aquarium: The Relationship Between Alkalinity And pH ? Advanced Aquarist | Aquarist Magazine and Blog
http://www.advancedaquarist.com/issues/may2002/chem.htm

 

[rock_lobster]

It's weird because I have 2 tanks side by side one is too low 7.8-8.15 and the other is too high (or okay) 8.1-8.5. The difference are the low pH tank is better skimmed, has more circulation and way less feeding. Quite a conundrum.. only thing I can think is the heavy feeding is boosting algae growth and the low flow is not fully aerating the water assuming the whole home CO2 may be slightly high as seen in the more aerated tank. Both tanks run same alkalinity, mag and calcium.

 

[Randy Holmes-Farley]

It's weird because I have 2 tanks side by side one is too low 7.8-8.15 and the other is too high (or okay) 8.1-8.5. The difference are the low pH tank is better skimmed, has more circulation and way less feeding. Quite a conundrum.. only thing I can think is the heavy feeding is boosting algae growth and the low flow is not fully aerating the water assuming the whole home CO2 may be slightly high as seen in the more aerated tank. Both tanks run same alkalinity, mag and calcium.

Photosynthesis and lower aeration/flow will lead to higher pH in a high CO2 home. :)

 

[rock_lobster]

Well tried doing that and it didnt work. Maybe adding just pure nitrate or phosphate would but in this case feeding more and lowering flow did not help in the lower pH tank. Its actually dropping down pretty low to 7.7 today lowest in a while. I still dont understand how 2 nearly identical setups can have such vastly different pH.. I just checked both pH probes with 10 and 7 and they are 100% accurate. So I'm not sure whats going on.

 

[Randy Holmes-Farley]

Well tried doing that and it didnt work. Maybe adding just pure nitrate or phosphate would but in this case feeding more and lowering flow did not help in the lower pH tank. Its actually dropping down pretty low to 7.7 today lowest in a while. I still dont understand how 2 nearly identical setups can have such vastly different pH.. I just checked both pH probes with 10 and 7 and they are 100% accurate. So I'm not sure whats going on.

Tried doing what? I would not recommend feeding more as a way to increase pH.

 

[rock_lobster]

Tried doing what? I would not recommend feeding more as a way to increase pH.

Yep tried that no success just more algae.

 

[Randy Holmes-Farley]

OK, thanks. :)

 

[rock_lobster]

Does the livestock make a difference the low pH tank has a lot of very large zoa colonies and greenstarpolyp while the other tank is all mushrooms. Same amount of fish in each.

 

[Randy Holmes-Farley]

Does the livestock make a difference the low pH tank has a lot of very large zoa colonies and greenstarpolyp while the other tank is all mushrooms. Same amount of fish in each.

More organisms will release more CO2 at night (lowering pH), and more photosynthetic organisms will consume more CO2 during the day (raising pH). I'd expect moving organisms such as fish to release far more CO2 than corals.

Also, perfect aeration with normal air, however, eliminates all pH swing and low pH issues. :)