buffering at a low ph?

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J

jestes

Feeder Fish
MFK Member
Feb 1, 2010
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Memphis, TN
I've got a question for the water chemists out there. Is there anything that buffers aquarium water at a low ph? I'm looking for something around 6.5. My tap water comes out at 7, but its not very stable. In the past I've had ph crashes in even lightly stocked aquariums, so that leads me to believe I've got a fairly low kh. For that reason, I've always added crushed coral to my tanks. As a result my ph is always rock steady at 7.6. The issue is I would like to start keeping some fish that really need a ph below 7. I'm just afraid to remove the coral for fear of a ph crash. So, is there anything that will give me a ph of 6.5 but still keep it rock steady?

Thanks in advance!
 
Think there are a number of commercially available products that raise KH without affecting PH. Baking soda will work also though to raise KH and have minimal affect on PH.
 
Baking soda is Sodium bicarbonate, which will raise your pH through the roof. A teaspoon in 50 gallons will raise pH by about 0.2 - 0.3 (roughly) up to a maximum of 8.6

Waterlife do a '6.5 Buffer' which is a true buffer - your pH will go to and stay at 6.5, but it is phosphate-based like all commercial aquarium buffers. If your water is soft though, you wont need to add much.

You could use a mix of tapwater and RO water to get your water to 6.5, and add a little '6.5 Buffer' to stabilize it.
 
Is there any other kind of low ph buffer other than a phosphate buffer? It says right on API's website not to use their 6.5 buffer if you have live plants... I'm looking for something similar to crushed coral in that it will reach equilibrium and quit dissolving. I've googled it until I was blue in the face, but I couldn't ever find anything.
 
Rather than insisting upon a defined and unchanging pH (in this case, 6.5), it will be far easier to establish and maintain an acceptable pH "range" in which to maintain your fish...for example, 6.5-7. Since your tap water is already at 7, your only challenge then becomes preventing the pH from dropping below 6.5. This should be fairly easy to do with routine water changes. You will have to monitor the rate at which the pH in your tank drops from 7 to 6.5. If this rate exceeds the ability of a reasonable wc regimen to stabilize it, then you will have to supplement the KH, since you won't want to be performing excessive wcs. Since you want to maintain your tank at a slightly acidic pH, the fact that your your tap water has a pH of 7 and a low KH (in other words, is naturally somewhat soft), seems to be quite useful.
 
What about "less" crushed coral? It seems like some level of crushed coral will hold your water steady at 7.6, but there has to be a point where the CC is dissolving at its optimal rate and its not producing enough minerals to raise PH to the full 7.6?

I should note the above is purely speculation and I'm no chemist :)
 
Well I got a KH test kit today. Apparently my buffering capacity is pretty low. Its reading as 2 straight out of the tap. That's good for being able to lower the ph, but I'm just concerned with being able to hold it there without CC... I know peat lowers the ph, but would that and CC cancel each other out?
 
Seachem has both an Acid buffer and Alkaline buffer which you can mix in various proportions to achieve whatever resultant pH you desire. check them out on the Foster&Smith web site. Your LFS may even stock it. I use it and it works great in my 535 gal tank.
 
I just got done reading about the Seachem products. Ill have to use their carbonate based instead of the phosphate based buffers. My tank is planted... have you run into any issues with ph fluctuations?
 
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