Low pH

[Slickdonkey]

Should I be worried about my low pH? It runs from about 8.2 down to 8.0 (or even 7.96) depending on the time of day. System volume is about 275 gallons and I run reverse lighting in the fuge with some chaeto. Metal halides are on 8 hrs/day and VHOs about 10 (was thinking of upping this to 12 for extended viewing). I also use kalkwasser for all evaporation topoff.

I suspect the reason for this is excess CO2, because my sump and makeup water is under the house, which is not especially well-ventiliated. Also, if I take some of my water and let it air out in the ventilated garage for a few hours, the pH is around 8.35.

I'm thinking this isn't a big problem, but I'd like to keep the pH just a little bit higher (say 8.3 average) to put me more in the center of the "acceptable" pH range of 8.0-8.5.

 

[DonW]

Not a big deal but I do like to see mine a bit higher. Sound like you know the cause. You may just need to duct in some fresh air from outside.

Don

 

[Slickdonkey]

Yeah, I guess the real question is whether it's worth it!

 

[DonW]

Yeah, I guess the real question is whether it's worth it!

Sure, oneday you may actually have a problem that amplified by the excess co2.

Don

 

[Brenden]

A piece of duct and a fan should not run much more than $30

 

[LakeEd]

you might try running the input air for your skimmer out the nearest vent under your house. Just add more 1/4" tubing... I think 25' runs about $4.50???

 

[Slickdonkey]

Hey that's a good idea... Normally my ozone is hooked into my venturi, but I turned it off for a few days to see what the effect is. In the meantime I could hook it up to a vent.

 

[Jeff]

Sounds like a great time to start adding Kalk?

 

[mattseattle]

Jeff - yeah he stated he drips Kalk in his first post.

 

[Slickdonkey]

Well I came across some interesting reading, so I'll leave some breadcrumbs for whoever comes across this thread:

Solutions to pH problems

High pH: Causes and Cures (talks about CO2)

Anyway this supports my theory that excess CO2 is the problem. Check out the graph in the second article. My alkalinity is about 3.5 meq/L and pH around 8.0, so you can see where my approximate carbon dioxide level is.

 

[Brenden]

Would the skimmer even pull from the outside with that much tubing?

 

[Jeff]

"Jeff - yeah he stated he drips Kalk in his first post."

Doh!

"Would the skimmer even pull from the outside with that much tubing?"

I have low ph problems in the winter and I use a aqualifter to bing air to the venturi of my skimmer.

 

[Boomer]

Slickdonkey

At-ah boy posting tha stuff to read

Brenda

Yes, I have a guy in the RC chem forum doing that.

 

[Brenden]

It just seems like a 1/4" tube 25 ft long would require a lot more suction than a skimmer would provide....I believe you

 

[Sherman]

I also have a CO2 problem, and have posted about it before. I have a 4 year old house in CA, where they're Nazi-Strict about energy efficiency. They build houses air tight around here nowadays. Typically, I see a pH range of 7.8 - 8.2, but that goes down in the winter, when we can't open up the house. Eventually, I put an air pump outside and ran a 1/4" line into the skimmer for constant fresh air aeration. It might have helped, I'm not sure.

Here's a link to that other board, where I started up a thread about it:

http://www.reefcentral.com/forums/showthread.php?s=&threadid=487458

 

[Slickdonkey]

Well I set up an air pump next to an outside vent and ran some airline tubing -- it didn't help. In fact since I recalibrated my pH probes it looks like I'm really getting a pH of about 7.9-8.1. I'd really like to raise that a bit.

I guess I could try actually moving the pump outside instead of next to the vent.

 

[mattseattle]

yo donkey - how long did you let it run for?

 

[Slickdonkey]

Couple days.

 

[Sherman]

I found the air pump injected into my skimmer may have helped, but it didn't make as big of a difference as surface agitation over the entire surface of the tank. Because of that, ambient air will always win. Oh well....

 

[Slickdonkey]

Yeah Sherman I think I have the same problem. I am in an older leaky house but I think having my sump under the house is a contributing factor. Thanks for the links, they were interesting but don't really give me a clear course of action.

At the moment a pH of 7.9-8.1 is not going to kill anything but I'm worried about adding a calcium reactor in the future.