pH and Buffering problem

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buggeek

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Dec 12, 2003
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I have a 90 gallon freshwater tank that has been up and running for about 4 years. I been having a ongoing problem with pH. Here are the stats:

pH - ~5.8
KH 0-40
GH 150

I would like a non-chemical means to fix this problem. I think coral is the way to go but how much should I use to bring the tank to 6.5 - 7. The tank is mostly filled with numerous tetras and rasboras. It also includes 3 large Hoplosternum littorale catfish (around 7-8"). I am trying to give two of them away as they are very messy and scare the other fish (see classified forum). Any help would be greatly appreciated! :help:
 
Have you been keeping up with waterchanges? If you have test your tapwater it is probably very soft and low in kH. I have a similar problem and I remedy it with a teaspoon of Sodium BiCarbonate (Baking Soda) per 10 gallons which raises your kH by 4 degrees. My Alkalinity tests at 40 ppm out of the tap or about 2 degrees. Add the baking soda slowly not to stress your fish over the course of many days with the waterchanges. That will bring your pH and KH up. I use plain old Arm and Hammer Baking Soda. The unscented variety.
 
Or, you could get Seachem Neutral Regulator. It raises (or lowers) pH to exactly 7.0 and it stays there.
 
First of all, how are your fish. Are they fine at that pH? If so, you couls leave it like that. If they have been there for 4 years you should leave it alone. In fact, trying to change the pH may lead to rapid changes that will harm more your fish than a low/high pH reading.

First thing you need to know is your tap water pH and Kh. If it's high (let's say over 6.5) and it drops when you add it into the tank, consider this:

This might mean that your filter is clogged or dirty. This leads to underfiltration and excessive production of acids. To correct it, clean your filter media in old tank water and put it back into the filter. If it get clogged again too soon, it means your filter can't handle the amount of wates being produced by the fish. You need a larger filter.

Do you have wood in the tank? Some woods reduce your pH. If this is the case, you could try removing it for some weeks anbd monitor the results.

Sometimes, making more frequent weater changes will help you reduce your Ph lowering. You should be doing a 50% water change weekly for the amount of fish you have there. If you haven't, try doing 25-30% water changes every two days for two weeks and monitor the results.


If you tap water ph and kH is low:
You'll need to buffer it. You can add crushed coral to the filter. Put a little in there (half a handful) and wait two days. monitor and add more if needed. Coral will start raising your pH until a certain level (7.8 max, I think). When Ph reaches this level, the reaction beetwen the coral and acids will stop, so your pH won't rise beyond that point.
 
Tap water:
pH ~ 6.5
KH = 80
GH = 75 -150

Water changes and gravel clean every two weeks
Filter cleaning once a month
One piece of driftwood is in the tank.

As stated I've had this problem for awhile. The reason I am trying to fix it now is that I am transitioning it over to a bunch of smaller fish from a few large fish. Some of the bunches of tetras I have added have died over night. It is hard to cash in on the pet store guarantee when your pH is that low. Plus, I hate having fish die on me.
 
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Try letting your tap water sit for 24 hours and then testing for PH.

I have low PH out of the tap..hardly registers 6,but if it sits overnight it climbs to 6.8

The PH in my tank sits at 7.

I don't know what would make PH drop that low,you're losing .7 from tap to tank.

You said you're transitioning your tank,have you moved the big fish out yet?

If so,I'd worry about fixing the problem before adding fish,but make sure you add something to keep it cycled.

If not then try the crushed coral,it probably would last longer with infrequent need to change out..I don't know about the baking soda,maybe someone else could tell you how often you'd need to add it to keep the PH level.
 
Tap water:
pH ~ 6.5
KH = 80
GH = 75 -150
Click to expand...

Tap water co2 levels roughly 36 ppm.
Atmospheric co2 is going to land about 2 or 3 ppm once the water equalizes and then your tap pH will be about 7.6-7.8. This is assuming no phosphate buffers.
The tank sounds to me like it is in the state of Old tank syndrome, if your tap has had 4.6 dKH all along.
You will need to start with very frequent (2-3 a day usually works best) low volume (10%- 15%) water changes until the parrameters raise to a stable level, It may take several days of the mini water changes to get things stabilized. The small amount of Kh you add from the tap will be dilluted a lot, and consumed fairly quickly (thus the need for frequency). You will then need to develope a maintenance routine that keeps the tank stable. Here is an article that explains OTS, how it works, what causes it etc.
http://www.aquasource.org/CMS/modul...ons&file=index&req=viewarticle&artid=7&page=1

IT will be difficult to maintain a stable tank and not get the Ph above 7.4. The fact is that a tank without KH is not stable, and a tank with Kh is not acidic. Your fish won't care when it comes to Ph. they would rather have the stable healthy environment than the swings of Ph shifting in an unbuffered tank.

Even if you could maintain Kh right at 1 dKH (17.9 ppm) your ph will be in the range of 7.0-7.2 but maintianing Kh right at 1 degree will be a struggle in itself. IF you maintain things at the same level as your tap water you'll be in great shape, and have the ability to do whatever whenever water changes as needed. If tank and tap are different parrameters as is your current case then you are limited to smaller water changes and more care must be taken.
dave
 
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