pH issues...

[Aquafreak]

My water in my 300 acrylic keeps rising to 8.0! Here's the details:

Tap Water - 7.0 (as tested every week for the last 6 weeks)

Water in my 150, 2 days after 50% water change - 6.8

Water in my 300, 2 days after 50% water change - 8.0


Both tanks have the same large rocks, same plastic plants, and I would say each tank has a comparable amount of driftwood as compared to the individual tank size. Substrates are different for each tank, but are from the same manufacturer and both claim to be acrylic coated and inert in freshwater. I also understand the whole CO2/02 & pH thing, but I don't really see it playing in here as both tanks have about equal aeration. Water temps are comparable. Salt rate is identical in each tank.

What's going on?

 

[Aquafreak]

Anyone have any suggestions?

 

[Nic]

what kind of substrate is it?

 

[Aquafreak]

I'm not sure of the composition. It resembles river bed substrate.

 

[kzimmerman]

Something is probably raising your carbonate hardness. Do you have any coral, coral rock, limerock, seashells, or anything similar in it? Any rock with any degree of white in it should be checked. A quick check is the acid test. Take the rock and drip a few drops of pH down on it, or vinegar. If it bubbles, it will raise the carbonate hardness of your tank, thereby rasing the pH. What are you keeping in it? Any particular reason your worried about the pH?

 

[haynchinook334]

Add some drift wood to the tank.

 

[kzimmerman]

Driftwood might work, but it's acidifying properties are not that great. I've got plenty of driftwood in my 55, and it doesn't even dent my 7.8 pH at all. If you really want to treat it, add some filter peat and activated carbon to your filter. The peat will lower the pH and carbonate hardness, the activated carbon will remove the staining from the water from the peat.

 

[Aquafreak]

Add some drift wood to the tank.

There's already a lot of driftwood in it. I know that wood can help to soften the water, but it isn't doing so here. It has to a small level in my 150. Thanks for the input though.

Something is probably raising your carbonate hardness. Do you have any coral, coral rock, limerock, seashells, or anything similar in it? Any rock with any degree of white in it should be checked. A quick check is the acid test. Take the rock and drip a few drops of pH down on it, or vinegar. If it bubbles, it will raise the carbonate hardness of your tank, thereby rasing the pH. What are you keeping in it? Any particular reason your worried about the pH?

I've been down the "which rocks to use" road and tested them all with HCL. Rocks are inert. I'm keeping mostly South American species like silver arowana and peacock bass, and they came from a tank where the pH was 6.0-6.5.

I understand your Peat idea, but my questions still remains. Why does the pH rise to 8.0 in my 300, when it drops to 6.0 in my 150? Same water. Same carbonate hardness. Same general hardness. Same everything!

 

[Knowdafish]

There's already a lot of driftwood in it. I know that wood can help to soften the water, but it isn't doing so here. It has to a small level in my 150. Thanks for the input though.

I've been down the "which rocks to use" road and tested them all with HCL. Rocks are inert. I'm keeping mostly South American species like silver arowana and peacock bass, and they came from a tank where the pH was 6.0-6.5.

I understand your Peat idea, but my questions still remains. Why does the pH rise to 8.0 in my 300, when it drops to 6.0 in my 150? Same water. Same carbonate hardness. Same general hardness. Same everything!

What kind of filtration and what's in your filters?

 

[Aquafreak]

Wet/dry sump with lava rock, bio-balls, scrubbies, and mechanical filter media.