# Rapid PH Drops Between Water Changes



## Piranha Dan (Nov 11, 2007)

I'm experiencing rapid PH drops between water changes. Both my tanks go from roughly 6.6 right after a water change to an even 6.0 3 days later. Is this due to the water being too 'soft'? If so, can I correct it by adding crushed coral to my filters?


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## CLUSTER ONE (Aug 2, 2006)

Piranha Dan said:


> I'm experiencing rapid PH drops between water changes. Both my tanks go from roughly 6.6 right after a water change to an even 6.0 3 days later. Is this due to the water being too 'soft'? If so, can I correct it by adding crushed coral to my filters?


Do you have any driftwood or peat in the tank?


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## Piranha Dan (Nov 11, 2007)

The only dirftwood in the tank has been there for a year and a half.
Sorry, left out some important info--I've moved recently. I don't think this is a problem with my tank it's just the new water at the new location. I went from a well to town water, That's why I was thinking it was a hardness issue.


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## Piranha Guru (Nov 24, 2005)

It is a kH (buffering/alkalinity) issue...kH buffers the water against rapid pH swings. You can use baking soda to up the kH to a level that should resist those fluctuations and adding crushed coral can help too. Hardness or GH is something different. I have water that registers as "soft" in my classroom tanks, but the school water has a very high kH and as a result, a very high pH.

Get a kH test kit and test both the tank and tap water to see what is going on so yøu know how much you need to buffer it to keep a steady pH.


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## Piranha Dan (Nov 11, 2007)

Thanks Bio-Teach. Baking soda did the trick for now, I'll pick up that test kit and some crushed coral for a more permanent solution in the near future.
So, if I have this straight, the difference between KH & GH is that GH is the hardness of the water and the KH is the Buffering capability?


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## Piranha Guru (Nov 24, 2005)

Piranha Dan said:


> Thanks Bio-Teach. Baking soda did the trick for now, I'll pick up that test kit and some crushed coral for a more permanent solution in the near future.
> So, if I have this straight, the difference between KH & GH is that GH is the hardness of the water and the KH is the Buffering capability?


That is correct...if you can keep your tank at an ideal kH, then adding tapwater with a slightly different pH shouldn't cause those swings. Don't let it get too high though or you may find your pH creeping up as it won't be able to drop. There is a chart somewhere that shows ideal kH for certain pH. I'll see if I can find it!


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## Piranha Dan (Nov 11, 2007)

Thanks, apprectiate it.


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## Dr. Giggles (Oct 18, 2003)

Do you have any filters and/or softeners hooked up to your tap water ?


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## Piranha Dan (Nov 11, 2007)

I have a whole house filter I put in when I was renovating the place. One of these:

http://www.lowes.com/lowes/lkn?action=prod...&lpage=none

It's not a softener/conditioner though just a filter.


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## Dr. Giggles (Oct 18, 2003)

That very well may be your problem if the filter is removing carbonates. Your best bet is to either place a limestone in your tank or fill a large nylon filterbag with crushed coral and place it into your filter. Also be careful not to do too large a water change at once. In your case it is best to do multiple small changes. Confirm with a kH test of your tap water. My bet is that it is under 5dkH which is optimum/minimum for steady pH. If somehow you can rig a hose for your water changes from the water source, not the filter, that may work for you. All depends on kH testing at both ends (filtered and non filtered)


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## Piranha Dan (Nov 11, 2007)

Thanks for the info. Still waiting on a KH test kit, so I'm still not exactly sure what the level is, but since the baking soda solved the problem I'm guessing that low KH is what's causing the problem.
Unfortunately using the water source isn't an option unless I start using one of those chemicals that removes chlorine (town water), so I guess for a long term solution I'm going to have to use crushed coral. Next time I clean out the XP I'll add a bag of it.
One thing I'm still curious about: Will adding the coral to my filter cause the PH to rise, or will it just make it hold steady longer? For example, I put my low KH water into the tank at a PH of 6.6, will it go up before it starts going down like normal between water changes or will it hold steady at 6.6? I saw a huge jump when I added baking soda to the tank (all the way up to 7.6, might've added a bit too much) that concerned me. Didn't seem to really affect the fish but I know big jumps like that can stress them.


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## roccov12345 (Sep 26, 2008)

Did the PH drop back down? Using the baking soda trick, for me anyway, only temporarily remedied the problem. You need to stabilize the buffering capacity of the water. I had read somewhere a good way to test your tap water buffering capabilities was to:

A) pour tap in a glass and test the ph

B) let it sit for 24 hours and retest the PH

C) Compare the two results. If you notice that there is a significant difference between the two, you'll obviously know that the KH or buff cap. of the tap is poor. Is your tank planted, CO2? If not, I know PH of 6.3 seems very low, but I'm running those numbers consistently with no negative effects. Might be something to contemplate as I've battled with this issue for quite some time with no real remedy.


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## Piranha Dan (Nov 11, 2007)

Actually, once I added the baking soda, It didn't drop at all for a week. Held steady at 7.6 which makes me think maybe I put too much in? I used 1/2 cup to treat 120 gallons.
Still waiting on the damn KH test kit. Tried to be nice and buy it locally and the damn guy at the LFS forgot to order it TWICE







He screws me again and I'll just go buy it online (could've had the damn thing a week ago if I'd done that in the first place).


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