Hello all, long time lurker, first time poster. I know the focus of this site is the science of planted tanks, but it is the only place for fish related info online that I trust, so...

Is there actually any correlation between water hardness and fish health?
Much is made about how fish though as "soft water fish" can be successfully kept in hard water, but very little is written about keeping fish in very soft water.

I live in Portland, and the water out of the tap has less than one degree of either GH or KH. I am wondering if this is actually appropriate water in which to keep fish, or if I should be adding CaSo4, epsom salts and what have you.

Anyone have any actual info on how water hardness or lack thereof actually affects fish health?

-Thanks

Not too much, most folks have excellent results hoiwever, if they properly acclimate hard to soft water.

AF cichlids are a classic case. Rainbows etc?
They do great. Some Tangy's need special care.

Acclimate very slowly over time and they generally do well.
Also, you can add GH, this is what most of the hardness salts are comprised of in many places, not so much bicarbonate(KH).

Add GH booster(Grumpy has some right there in the your local town. See Rex Grigg)

Regards,
Tom Barr

I bought the GH Booster from "aquariumfertilizer.com". The only instructions on dosing was to look on the BarrReport.com.

I have a 70 gallon storage tank for changing water weekly. The water from my tap is very soft (the GH does not even register with a API test kit). I'd like the hardness to get up to 3.0 -5.0 starting with 20% weekly water changes. The pH of my tanks range from 6.6 to 7.0.

Norm

You can use the SeaChem EQ chart, it's relatively close to what the Gh booster will do.

The GH booster will add a bit more than the SeaChem will.

But GH is a rough guide anyway.............not some critically measured micro nutrients, same with K+, few folks fret over that as long as they have non limiting levels.

The other way is to simply add some to the tank and measure the volume, wait, 4-8 hours, then measure.

Or you can add a 5 gal bucket of water and add enough to get 3 GH, make sure to mix and have a powerhead in there to keep it mixed and well circulated.
It'll be a fair amount if the GH is low in the tap.

These are all simple methods to get a handle without going over board and spending more time than the question is really worth.
GH is measured in 18ppm increments, more than most K+ estimations.

I'm not precisely sure the analysis for GH booster to tell the truth, but I alos know it's not critical knowing that either.

If it makes you feel a bit uneasy, you can spend more on SeaChem's, it's got the guaranteed analysis there, home made GH booster does not.
But it's 10x cheaper.

You can make your own also(my choice), then you know(if you feel it's important, which, to tell the truth, no, it's not, unless you want to do experiments etc)

As long as you add 3:1 Ca:Mg from a GH booster, and you have enough for a given rate of growth, then there's little to worry over.

Regards,
Tom Barr

A lot depends on the fish. I had terrible success with (supposedly hardy) livebearers (platies and guppies), until I started adding Ca and Mg to my tanks for my plants. Now my mollies and guppies are doing well. However I had some tetras I couldn't kill for years, with 0 KH and GH in my tank. I also have a bunch of bettas that have gone from 0 GH to 100ppm+ with no apparent effects either way. Acclimation is part of it, but some fish just may not do as well with one extreme or the other. For someone who isn't interested in breeding, it's probably best to just be sure to acclimate slowly and you can probably keep most fish.