Low PH question

[Ernie C]

Just a question as I’ve learned not to chase ph the hard way. My ph always wants to drop below 7.8. I have been dosing kalk opposite to the light cycle to keep it stable. So it stays at about 7.9-8.1. My calcium and alk are at 440ppm/10.5 dKh and I try to keep them stable at around that. My question is, does the amount/size of corals algae affect ph? I’m thinking perhaps there isn’t enough photosynthesis going on in the tank? Is this even a factor? I’ve tried airing out the house and can’t get skimmer intake from outside but not sure inside CO2 is the issue.

I have small coral pieces and recently battled algae and Dino’s and hopefully turned the corner on those fronts knock on wood, but don’t have a lot of algae growth except for in the sump. Coraline algae has really taken off in the past month or so not sure that is even a factor. Any insights would be awesome.

 

[Auto-pilot]

Ok ph and alkalinity are related and I will do my best to explain how. Alkalinity in our hoby actually refers to the amount of carbonate we have in our system where ph is the measure of how many ions are needed at the current moment to neutralize the tank. When you add a buffer you are in a round about way changing the co2 to co3 in your tank. The higher the concentration of OH ions the higher your alkalinity will be.
Ph measures the carbonate but swings because as carbon dioxide is made in the tank it creates Carbonic acid lowering the ph. Co2 chemically bonds with water to create carbonic acid. At night carbonic acid levels rise bringing down Ph but the amount of carbonate in the water stays the same and alkalinity is not as affected as Ph. You can get your Ph and your alkalinity and actually measure the amount of CO2 that is in your tank because of this relationship.
If I messed this up at all please correct me

 

[Auto-pilot]

Instead of dosing to maintain Ph I would add algae or something to lower the amount of carbon dioxide in your tank. Something else that helps people is sucking air from outside to feed their skimmer

 

[Ernie C]

I can’t feed the air from outside really although I have tried it temporarily and didn’t see much of a difference. And I leave the back door open often for my dogs. I figured kalk was a good option to dose at night to maintain light cycle ph and also maintain calcium and alk. I bought bionic two part but haven’t used it yet. Have to read up on dosing etc. I have a nice size chaeto mass in the refugium. Is there any macro algae better suited to use CO2?

 

[Auto-pilot]

I can’t feed the air from outside really although I have tried it temporarily and didn’t see much of a difference. And I leave the back door open often for my dogs. I figured kalk was a good option to dose at night to maintain light cycle ph and also maintain calcium and alk. I bought bionic two part but haven’t used it yet. Have to read up on dosing etc. I have a nice size chaeto mass in the refugium. Is there any macro algae better suited to use CO2?

I use Chaeto as well a light cycle opposite of my daytime schedule. I would think that that if by dosing it makes your alkalinity unstable/ too high the Ph swing would actually be less of a problem. What kind of Ph test are you using???

 

[Ernie C]

I also light my sump opposite the light cycle and have the dosing to dose every hour while the lights are off and calcium and alkalinity stay stable. I technically dose with calcium and alk in mind, but do it over night so it helps stabilize the ph. I’m measuring ph with Neptune apex ph probe. It’s only like 4 months since originally calibrated. I have an api test I randomly use to see if they match but hard to tell with api but seems to match. I’m not having any apparent issues but just curious why ph tends to want to drop so low.

 

[Auto-pilot]

I also light my sump opposite the light cycle and have the dosing to dose every hour while the lights are off and calcium and alkalinity stay stable. I technically dose with calcium and alk in mind, but do it over night so it helps stabilize the ph. I’m measuring ph with Neptune apex ph probe. It’s only like 4 months since originally calibrated. I have an api test I randomly use to see if they match but hard to tell with api but seems to match. I’m not having any apparent issues but just curious why ph tends to want to drop so low.

yeah the only thing I can think of is your test is not accurate or your CO2 is actually high at night