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Discussion Starter · #1 ·
I have a 55G tank that has been set up for a year now and the KH keeps going up, I have not changed anything about the tank since setup (except plants & fish).

When I first set the tank up the KH was 6/7, then it went up to 9 over time. Last night I tested the KH and it was 16 :neutral:

May tap water has a KH of 3 and my two other tanks KH stay at a steady 3/4.

What could be causing the rise?

I was thinking either RO water or peat to lower the KH... Which way would you suggest as being the simplest?

My GH is 18 if that helps... I've never had this problem, so if you need more info let me know.
 

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trenac what kind of substrate do you have? Any rocks in the tank? I would use R.O. water its easier and more controllable than peat. I have never got peat to do anything but tint the water brown.
 

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It could be something in the subtrate. What subtrate are you using?

Since your kH from tap water is pretty low, I don't see how RO will help bring it down since it's something in the tank that is causing the kH to rise in the first place. But to answer your question, RO is definately the way to go. It will turn out to be cheaper and more effecient in the long run. Peat is too unstable and ineffecient, it also requires a lot of cleaning before it can be used and it needs changing often to keep the parameters stable.
 

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Discussion Starter · #4 ·
The gravel is a mixture of Flourite and regular natural gravel. The only decor in the tank is a large piece of driftwood.
 

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I would look into exactly what 'natural gravel' is. If from Florida, I can guarantee it will be high in CaCO3 which would cause an increase in kh. Of course, another question which I would look into is to make sure your test kit hasn't gone haywire.
 

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Discussion Starter · #6 ·
Bert... I don't know where the gravel was collected from but it was bought from Petsmart, if that helps.

The test kit is fine because the readings on my other tanks are correct.

* Another question... When adding RO water after a waterchange, do I add all RO water or mix half and half with tap water?
 

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trenac the amount of ro water u will add depends on what Kh/Gh you are at now. for example if u have gh of 12 and want a gh of 6 then you would do a 50% water change with 100% ro water. Ro water has a 0 for kh/gh. If you know what your tap water has in it then you can mix the ro with the tap to reach what you are targeting for kh/gh. You may need more ro at first to get the tank where you want it and then figure your mix after that. Thats what I do. But if your substrate is leaking kh/gh then the ro will just be a temp lowering. I know many people using onyx sand and do water changes with straight ro and still have high kh/gh levels. The best bet is to find out what is causing the raise in kh/gh, and go from there. Petsmart gravel shouldnt buffer at all, and neither does the flourite. Kh raises from calcium breaking down. Do u supplement calcium in any way?
 

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Discussion Starter · #8 ·
Chiahead... The only calcium I dose is the Kent Grow which has 0.15% of calcium in it.

I wish I knew what is making the KH rise, I have not made any changes in the tank since it was setup a year ago; so it baffles me way the KH is increasing over time.

Do you think it could be the large piece of driftwood?
 

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I think the drifwood would do the opposite. Release tannins and poss lower the kh. But I dont think it will raise it. Not to knowledgable about the driftwood though.
 

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I don't know specifically what effect Calcium Citrate has on KH if any at all in the amount you dose.

I would be suspicious of the Top Fin gravel that Pet Smart carries. Is it similar to the Estes brand that is painted/varnished/coated or whatever you want to call it? I have seen the Estes type loose it's coloring many times in LFS tanks that sell it.

If you have any extra gravel, try putting it in a glass of water for a few days and see if it has any effect on the water. I guess if you don't have any extra, you could always pull some out of the tank and try it that way. That would be the only way to be sure it is the gravel and not something else causing your CO2 to rise. If it is the gravel I would start using RO to drop the KH.

On the subject of using RO water, be aware that a 50/50 mix of RO and tap will not only decrease your GH by half, but also your KH by half. This could leave you with a GH of 9 dGH and KH of 1.5 dKH.

Using peat would be the simplest method but it may not be the most dependable. You would have to experiment and see how much you would need to add to a certain volume of water to get the levels you want. Peat will also discolor the water. A lot of folks at the apistogramma forum like to use peat, but they aren't concerned with the tannins. While the fish will probably like the tannins, depending on what type of fish you have, it will also decrease the amount of light available to your plants. I played with peat trying to soften my water and didn't like the results very much.
 

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Discussion Starter · #11 ·
Thanks for the info Matt... I think I will try RO water first, I don't want my water to be discolored. The gravel I got from Petsmart did not have any coating on it as far as I know.

* Would lowering the KH by half all at once have any adverse effects on the fish?
 

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Do you know anyone with a pool or hot tub? If so, they'll very likely have some muriatic (aka hydrochloric) acid. Maybe even a local pool maintenance company can give you a little bottle of it, or maybe a pool supply shop might have an open bottle they can give you some from. (Ugly grammar there...) An empty glass cough medicine bottle (or eye-dropper bottle, just don't get acid on the rubber bulb) works well for transport.

From the description of your tank, the only things that could be raising the kH are the gravel or the driftwood. If you can get some muriatic acid (or any other strong acid for that matter - the muriatic is just readily available as pool maintenance stuff) it'll tell you in a flash which it is. That's how I found that the really pretty rocks we were using for a cave were causing our kH and pH to rise. Pull the driftwood out (if it'll come out, that is) and take out a scoop of the gravel, then put acid on both. They'll fizz if they're acid reactive, and if they're acid reactive they'll leach into the water column. I do acid-safe testing of gravels and such in a glass (or ceramic) bowl.

Caveats:
  • don't test things while they're in your tank (should be obvious, I know, but...)
  • put acid on the things, don't drop the things into a pool of acid
  • follow all the other warnings on the label of the acid bottle or box

Another strong acid that's fairly readily available is sulfuric, which is used in car batteries. Most car batteries are shipped dry (except the sealed ones) and the auto parts store adds the acid on-site. Ask them for a little bottle of it - the stuff is really cheap (as is the muriatic) so someone should be willing to part with some for free.

Standard disclaimers inserted here - we're talking nasty acids, use at your own risk, yadda yadda. ;-) Sue me if you want - my only asset is a frozen gourami (it died last weekend, and my daughter and I are going to dissect it.)

Happy hunting!
 

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Trena, I agree that it is most likely your gravel. Are you using the same mixture in your other tanks as well? I work at All Oddball Aquatics which is a local fish store in Pittsburgh and I have dealt with this problem many times. As the old saying goes if I had a dime for every time… I’d be a millionaire. When the problem arises with a customer the first question that I ask is “Where did you get your gravel?” Nine times out of ten they say Petco or Petsmart. So I tell them to bring a couple pieces in and spray it down with muriatic acid like Glen said. It fizzes like crazy and then I break the bad news to them. Although I admit it is strange that you are having this problem after a year of being setup, I do believe that testing your gravel is worth a shot. Good luck!

Tim Gross
 

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Discussion Starter · #14 ·
Thanks Tim & Glen... I will look for some acid this weekend and test the gravel and see what I get, I will post the results.

My other two tanks have Eco-complete (20G high) & straight Flourite (20G long) in them.
 

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Discussion Starter · #15 ·
I finally got around to testing my gravel. Instead of acid I used white vinegar. Once I covered the gravel with the vinegar it started bubbling, so that Petsmart gravel is causing my high KH. So this means I get to re-do my 55G tank, I was looking for a excuse.
 
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