Stunting and Very Soft Water - The Planted Tank Forum
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post #1 of 7 (permalink) Old 05-22-2013, 04:50 AM Thread Starter
Algae Grower
Join Date: Mar 2010
Location: Cape Cod, MA
Posts: 84
Stunting and Very Soft Water

I am noticing a lot of stunting issues in my tank. My local water report says that the average hardness in my area is 14mg/l of CaCO3. 1 dGH is equal to 17.8mg/l of CaCO3, so doing the math this puts my dGH at about .79.

Now I've heard time and time again that most stunting/poor growth issues are caused by poor CO2. So since the tank has no fish, I've cranked the CO2 to where I believe there should be no issue. The CO2 line is fed into the venturi of a Danner Mag 3 pump with fractionating impeller running on a closed loop. The water returns to the tank through 4' of tubing and fills the entire tank with microbubbles that I can clearly see reach every spot in the aquarium. The needle valve is open to the point that it is literally almost a constant stream of bubbles in the bubble counter. I think that should cover CO2

This leads me to believe that my stunting issues are caused by the very low GH of my tap water. I have a 12 gallon cadlights aquarium, which I figure actually holds around 10 gallons. I also just picked up a bottle of Seachem Equilibrium. About how much Equilibrium should I add to bring my GH up to optimal levels? And how soon can I expect to see improvements in plant growth if indeed my low GH is causing the stunting?

Thanks for anyone's help in solving this issue for me,
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post #2 of 7 (permalink) Old 05-22-2013, 06:28 AM
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I would try what the label reads, 1 tablespoon per 20 gallons. Adding 1/2 tablespoon would raise the GH by 3 points in a 10 gallon tank. If you see a positive change then consider adding a bit more. I believe changing GH can be hard on animals so you may want to move to the whole 1/2 tbs over a few weeks time.

My water isn't as soft as yours in fact I believed it to be on the hard side but adding a bit of GH booster I had really improved the growth of Rotala sp. in particular. Definitely worth a try! I saw healthy growth that very week, most of my plants are fast growing weeds if they are getting what they need.
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post #3 of 7 (permalink) Old 05-22-2013, 03:27 PM Thread Starter
Algae Grower
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Location: Cape Cod, MA
Posts: 84
Ok Kathy thanks for the advice. There aren;t any inhabitants in the tank yet, I've been trying to get some good growth out of the plants first. I'll try adding half a tablespoon and see where that gets me.

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post #4 of 7 (permalink) Old 05-24-2013, 10:56 PM
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Very low Ca and Mg can kill the plants. I am not surprised they are distorted or stunted on a near-starvation diet.

The new growth should start growing regular shape pretty fast.
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post #5 of 7 (permalink) Old 05-24-2013, 11:10 PM
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What's the ideal water hardness level? I have soft artesian well water and am having trouble with keeping my plants healthy and have covered about everything else. I just happened to stumble across this thread.

Last edited by jonnyboy; 05-25-2013 at 10:07 PM. Reason: Typo
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post #6 of 7 (permalink) Old 05-26-2013, 02:19 AM
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Very generally:
Soft water fish prefer a GH under 5 German degrees of hardness, and as low as 3dGH or less may be better for some, especially for breeding wild caught soft water fish.
Hard water fish prefer a GH over about 9 dGH.
Captive bred fish will usually handle a wider range of parameters than their wild ancestors.
Do enough research about the fish you will be keeping to set the GH at the right level, and to know if they can even be placed in the same water.

Almost all the aquarium plants we grow do not really care what the GH or KH are, as long as they are not zero.
Plants use calcium and magnesium in a ratio of about 4 parts Ca to 1 part Mg, so if you have a Ca test, look up how to do the math and figure out what the Mg is. (The math is not straight forward; it is NOT GH - Ca = Mg)
There are materials available to supplement just Ca or just Mg (Epsom salt) if one or the other is too low. I would only bother with this if I suspected a problem with either Ca or Mg levels.
A blend sold as GH booster is fine in most cases, but read the ingredients. Some contain sodium chloride, which is not the right material for a fresh water tank. Seachem Equilibrium and Barr's GH booster are good products.

Roughly half the aquarium plants we grow can utilize the carbon from carbonates (KH) and do not require CO2 to be added to the tank. Decomposing microorganismsand nitrifying bacteria also use the carbon from KH. Watch the KH so it does not drop below 1 dKH.
It used to be thought that KH under 3 degrees could lead to unstable pH, but many people running tanks with very low KH (Including me) have found that the pH can be quite stable (and quite low) even when the KH barely registers. The nitrifying bacteria are not very active, though, at low pH.

How I do this: My tap water is fairly soft, and already pretty good for soft water fish from hatcheries. Not so good for hardwater fish, or for breeding the most particular of soft water fish.
1) Research the fish. Figure out the optimum GH for the mix of fish in the tank. Start with RO for breeding soft water fish. Tap water for all other fish.
2) Set the GH to suit the fish. I use Equilibrium or Barr's GH booster to raise the GH.
3) Set the KH pretty close to the GH. (plus or minus 1-2 degrees) I use baking soda to raise the KH.
4) Let the pH do whatever it wants.
5) Add peat moss to the filter for black water fish. Add coral sand, oyster shell grit to the filter for hard water fish.
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post #7 of 7 (permalink) Old 05-26-2013, 05:27 PM
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Okay thanks! Good to know
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