Can't get PH above 7.8

[Richb5571]

I have a CO2 scrubber, a refugium and I dose 2 part solution daily with Apex DOS. Not sure what else to do. I have used aquavitro balance and PH goes up to 8.2 but 12 hrs later it settles back to 7.8

 

[Dkmoo]

What tesr kit do you use and have you done the cup test to confirm that it really is a co2 issue?

 

[Richb5571]

I'm going to try the cup test. I only use the Apex probe for PH but I'm getting a ph test today

 

[DC Reefer]

For your 2 part are you using soda ash? Soda ash raises ph better than sodium bicarbonate (use about half as much to get same Alk).
I would also check the calibration of the PH probe.

Also I would open the windows for a day and see if that raises your PH. If it does that would point to Co2 being the culprit.

 

[Richb5571]

For your 2 part are you using soda ash? Soda ash raises ph better than sodium bicarbonate (use about half as much to get same Alk).
I would also check the calibration of the PH probe.

Also I would open the windows for a day and see if that raises your PH. If it does that would point to Co2 being the culprit.

i just opened the windows today so I'm going to see if that has an impact. im using the BRS Soda Ash for my 2 part

 

[MichaelReefer]

I used Seachem Reef Fusion 2 to get my alk up to 8.5 then use Kalk to keep it stable.

 

[Richb5571]

I used Seachem Reef Fusion 2 to get my alk up to 8.5 then use Kalk to keep it stable.

so is it better to dose kalk vs. soda ash?

 

[MichaelReefer]

so is it better to dose kalk vs. soda ash?

I've had very good luck with Kalk so I stay with it. I stay steady at 8.4-8.6 pretty much any time I test. Having great coral growth.

 

[Dkmoo]

so is it better to dose kalk vs. soda ash?

Kalk functions both as a alk raiser and a co2 reducer. If the scrubber is dialed in properly and recirculating, it should serve similar purposes used in conjunction with soda ash. However, often times, due to the size of the scrubber/skimmer vs the surface area of the dt/sump/overflow and ambient air exchange thats pumping co2 back into the system, kalk has an easier time raising pH if the scrubber/skimmer is undersized for air exchange purposes.

Kalk users sometimes has to opposite problem - ph too high, leading to burnt tips and abiotic precipitation

 

[MichaelReefer]

Kalk functions both as a alk raiser and a co2 reducer. If the scrubber is dialed in properly and recirculating, it should serve similar purposes used in conjunction with soda ash. However, often times, due to the size of the scrubber/skimmer vs the surface area of the dt/sump/overflow and ambient air exchange thats pumping co2 back into the system, kalk has an easier time raising pH if the scrubber/skimmer is undersized for air exchange purposes.

Kalk users sometimes has to opposite problem - ph too high, leading to burnt tips and abiotic precipitation

Kalk is more of a alk holder than a raiser. Using something like Reef Fusion 2 to raise it, then kalk to hold it there is better. You just have to slowly raise it.

 

[Dkmoo]

Kalk is more of a alk holder than a raiser. Using something like Reef Fusion 2 to raise it, then kalk to hold it there is better. You just have to slowly raise it.

Doesn't the hydroxide provided by kalk strip out the dissolved CO2 to form carbonate and bicarbonate? Thus raising Alk?

Always thought the apparent decrease in Alk from kalk is the result of increase in alk consumption from calcification /precipitation due to pH increase instead.

Either way, agree when using kalk, supplemental alk dosing should be mainly bicarbonate since soda ash can cause too much ph impact.

 

[Sarlindescent]

There are multiple factors that determine PH in a reef, but they all are based off of CO2 is the water column. The biggest predictor is ambient CO2 in the house air. Opening a window helps this, but depending on how high it is, the tank ph can drop as much as 0.3. I invested in a CO2 monitor for my house and it helped quite a bit.

Another major factor is biological. Highly stock tanks will have more CO2. But more than that, bacteria produce CO2 when processing waste. Extra food or built up detritus can have major effect on the PH. The sand bed can effect this, but a more common problem is a dirty filter/sump. A lot of detritus can get trapped in the rocks as well. Using a turkey baster to blow them out can pull out a lot of detritus.

If weather allows, I would recommend continuing to air out the house. Then focus on cleaning out the tank. I recommend not doing a mass cleaning, but focus on a section at a time.