# GH increase



## rkymtn4 (Apr 22, 2005)

Something in my 29 gal tank is increasing the general hardness too much and I'm not sure what it is. Out of the tap, it's anywhere from 3-8 dH, and after a 40% water change, the tank will be around 13. Then it climbs +2 dH/3 days and will readily hit 25+ if I don't intervene. The pH is usually around 8, and the kH is about 2 or 3 if I add a couple tsps baking soda after a water change.

I recently tore down the tank from having soil packets under the gravel for a year, wondering if that was causing the problem, took out half the gravel, rinsed out the rest and added fluorite gravel for a 50-50 mix. Have a large piece of driftwood, 2 Ebo-Jager heaters, various plants and a Fluval 3 in-the-tank filter with just sponge-media in it and a smaller Fluval 2 with some porcelin hexes, a sponge, and a little charcoal(mainly because when the power goes off, the Fluval 3 won't start back up without heavy pounding). I don't have any decorations in there that would be leaching calcium/mag. Water does evaporate from the tank as it's not 100% sealed off, but this increase seems to be happening faster than the rate of evaporation.

Anyone have any ideas? I just use tap water with a little water conditioner. I wasn't vacuuming the gravel when there was soil in it, but I've returned to doing so with the fluorite. The tank/water looks fine, but I'm sure the steep incline in hardness killed off a bunch of fish awhile ago and I'm being cautious about adding new ones until this is stabilized.

Thanks for any suggestions-
Lynn


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## werner (Jul 6, 2006)

Welcome to APC!

Since it doesn't appear that you're adding any CO2, this might be due to a process called biogenic decalcification. Some plants (eg. _Elodea_, _Najas_, _Ceratophyllum_, _Vallisneria_) can get their carbon from the bicarbonate ion when CO2 isn't readily available. As a result of this process, calcium carbonate precipitates on the leaves (a sandy white coating), the pH increases (sometimes dangerously), and KH drops. More scientific detail here: Biogenic Decalcification

You might want to consider adding a DIY CO2 system.


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## rkymtn4 (Apr 22, 2005)

*Biogenic Decalcification*

Yikes! It'll take me awhile to comprehend all the info from that link, but looks pretty thorough - thanks! I haven't noticed any coating on leaves, but I do have tons of those little trumpet snails and I noticed one article mentioned them briefly. I was wondering about their shells being calcium, but will try to read more about it. I have not injected CO2 into this tank and wasn't wanting to mess with it, although I might consider an RO filter for water changes if need be. The pH & gH have always been high, but while the pH remains stable, the gH has been difficult to keep at a reasonable level lately.

Lots to study - thanks for the resource!

Lynn


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## Laith (Sep 4, 2004)

What kind of gravel are you using?


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## rkymtn4 (Apr 22, 2005)

The current gravel mix is 50-50: small sandblasting gravel I've had in there for 15 years and SeaChem's Flourite which does have minerals in it, and was advertised not to change the pH, but I wonder if it's affecting the gH. I just wrote them to specifically ask that question too.


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## Laith (Sep 4, 2004)

No, Flourite shouldn't affect your water parameters...

Very strange readings. You have a high (-ish) pH with very low KH and your GH goes up by 2 degrees every 3 days. It also sounds like your tap water has a KH of around 1 and your GH varies between 3 and 8?

At a KH of 1 your pH should be around 7. At a KH of 3 your pH should be around 7.5.

Two suggestions:

- Check/calibrate your test kits.
- Leave some tap water out in a bowl for 24 hours or so and measure the KH and pH. That'll give us a better idea of your true tap water readings (pH especially).


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## Left C (Jun 14, 2005)

I went to the water treatment plant near me and asked for one of their test reports. I told him the I have aquariums and I just wanted to know. He gave me a copy. The manager there was real nice and talked with me a while.

He told me that there are two places that I might get water from. The new plant and this old plant. He said that they switch back and forth between the two according to demand, maintenance, algae problems and debris at the new plant, etc.

I told him that I wasn't having any problems but it did notice that the GH and KH in my tap water changes sometimes. He told me that the changes probably occur when they switch back and for between the two water treatment plants.


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## rkymtn4 (Apr 22, 2005)

Thanks for all your suggestions! I'll try leaving some water out and testing it, and it would be interesting to see what's going on with the water treatment plant. I have noticed a variety of readings out of the tap, so that could be a factor, although the tank always goes harder than the tap. The Seachem folks responded that it wouldn't be the gravel either and recommended topping off the tank with distilled or filtered water and checking that. There's always a reason, whether I figure it out or not!


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