GH is very hard, need advice! - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 3 Old 07-03-2010, 10:49 AM Thread Starter
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GH is very hard, need advice!

While I was pregnant and feeling sick I totally neglected my aquarium. The java moss is taking over the entire thing and only two mollies are alive in there.

My aquarium is a 30 gallon hex.

I tested the water today. The pH is 60 mg/L. The GH is 220 mg/L Ca CO3.

According to the booklet the GH is off of the hardness scale and the pH is a little low?

This has happened in the past and I went to my local fish store with water samples and they told me exactly what to do to fix it. Our area has very hard water and while I was pregnant tap water (dechlorinated of course) got added to the tank. I normally buy reverse osmosis water to put in instead. Our LFS closed down due to the economy, so now I can't get any real life help! I wouldn't bother asking Petsmart...

I have a bottle of Kent Freshwater pH Stable that the LFS sold me a few years ago. I'm not sure if this is the correct thing to use now or how much to add. I don't want to mess it up any further!

Side note--I'm planning on ripping out most of the java moss soon, if that will make a difference in the water treatment or the tank cycle. There are a couple other small plants in there also that will stay...
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post #2 of 3 Old 07-04-2010, 02:00 AM
dfbiggs's Avatar
If you add peat moss to your filter it will lower KH and GH. If you make a DIY CO2 system you can lower only KH. Warning...the CO2 system will drop your PH drastically in a short period of time...I use this to control my PH...I need to have high GH and KH because I have snails/ inverts which need hardwater( calcium..minerals in the water)or they will deteriorate and die. Sounds like your best option is peat moss..

A side note..if you don't want your java moss I would love to take it off your hands..I have been trying to get a hold of some for my shrimp.

Hope this helps!


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post #3 of 3 Old 07-04-2010, 10:59 AM
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First off, do not use pH adjusters in a tank with fish, ever. There is a natural relationship between carbonate hardness (expressed as KH, GH is general hardness--these are related but function a bit differently) and pH. The higher the KH the more it buffers the pH to prevent it from fluctuating (a basically good thing). Using pH adjusting chemicals may cause the pH to shift but within 24 hours or less the natural buffers in the water will bring the pH back. This continual fluctuating pH is far more stressful on fish than leaving it where it is. And if the pH adjuster is continually added long-term, the point may be reached when the KH buffers are exhausted and then the pH "crashes" and usually fish die or are at the least severely weakened.

What brand of test kit do you have? pH is usually measured with the logarithmic scale from 1 to 14. I've never seen it expressed as mg/L so I'm not sure what that means.

Be careful doing water changes; if the tank pH is acidic (below 7) the ammonia produced by the fish changes to ammonium which is harmless. If the pH of the tap water is basic (above 7) and a water change is done, and the tank pH rises above 7 as a result, the ammonium changes back into ammonia and could weaken or kill the remaining fish.

I may have more advice when I know for certain the pH.


Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]
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