GH. How low can I go.

calihawker

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Jan 7, 2008
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What is the minimum hardness needed for plant health and growth. My tap water is pretty much stripped of minerals.

GH 12 ppm
total hardness 8.5 ppm
potassium ND
magnesium ND
TDS 5ppm
PH 8.2

I have been adding 3 Tbl. GH booster to get 150 gallons up to 3.5 dGH for each 50% water change. The problem is, it's hard to dissolve that much while I'm doing the w/c.

Tom, I know you mentioned to me in another thread that you only add 1 Tbl. during w/c in your 350 gallon project. Is the water you're using somewhat hard already?

I have scaled back on the lighting requirments for the tank and will be sticking with plants that have low to moderate lighting requirements, however I am currently growing out discus that will be moved over to the display in a few months and my main concern with water chemistry is keeping all the parameters constant while adding as little outside influence (chemicals) as possible.

Thanks!
Steve
 

jeremy v

Guru Class Expert
Apr 17, 2008
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Calihawker,

I have never used gH booster, but if you are having problems getting it to dissolve why don't you just use epsom salt (MgSO4 x 7H2O) for your magnesium and calcium chloride (CaCl2) for your calcium instead? They both dissolve in water very fast and very easily. Just don't dose them right at the same time (letting the powders land in the tank on top of each other) or they will react with each other and make a flaky white precipitate that takes a few hours to dissolve. That has been my experience anyways. I think they react with each other to produce CaSO4 temporarily. Then the CaSO4 takes a few hours to dissolve since it has a much lower solubility. Just dose one of them and wait a minute or so until it is fully dissolved and then add the other and you will be fine.

I also have 1gH water. My water department gave me recent test ratings of 11ppm Calcium and 6ppm Magnesium in my tap water. I just add Epsom salt and CaCl2 at about a 4:1 ratio of Calcium to Magnesium at each water change to bring my total gH up to at least 3 and always somewhere between 3 and 6 degrees.

I have heard that 3 is a good minimum for plants as long as it is a well balanced 3 with good amounts of both calcium and magnesium. My main experience as of now has been with fish only. I am pretty new to planted tanks still. IME, even soft water loving fish seem to be noticeably happier and healthier looking with at least 3 degrees gH. Anything less and their scales look less shiny and their activity seems to dwindle some. If I have less than 3 degrees gH in my water I begin to also see symptoms of magnesium deficiency in my pennywort plants (green leaf veins and yellow leaf tissue on older leaves), especially in tanks that are lower light and non-CO2 that don't get water changes much.

Have a good one, Jeremy
 

Tom Barr

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Jan 23, 2005
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You can go very low if you want to dose very frequently and add very little many times per day etc. Or dose a fair amount 1x a day, or more 3x a week, or even more 1x a week.

The question is less about how low you can go and more about what is practical dosing for you personally, some do not mind daily dosing, some 3x a week, some weekly , some none at all:)

You could add dolomite, that would dissolve fairly slow and add Ca/Mg.
Practical, easy, but not that precise.

the other big real question, why go so low if you can simply add more GH booster?
It will certainly help the plants and make them look better.

So lower is not better there.

Regards,
Tom Barr
 

VaughnH

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Jan 24, 2005
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If you start with water having a GH of 4 dGH for example, does that value continuously drop with time as the plants consume calcium and magnesium? It seems like it has to, but I may be missing something. As I understand the above post, you could theoretically drip in just the amount used up by the plants, continuously, and the GH would remain constant. This has to mean that with no water changes or calcium/magnesium additions, the GH constantly drops in the tank. The next obvious question is how fast does it drop?
 

jeremy v

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Apr 17, 2008
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I would assume that everything works just like how you mentioned Vaughn. The plants would slowly take up the Calcium and Magnesium just like any other nutrient, so you would need to make sure that you have enough to meet the plant's needs at all times and also ideally try to have a good minimum amount at all times just to keep the plants operating within an efficient zone of uptake.

I would also intuitively assume that more is better in as far as plants are concerned (as Tom said), and if Tom and I disagreed I would go with his recommendation, because he has a lot more experience with growing plants than I do, haha. I have never really used more than 6 degrees gH, so that's the only reason I stated 3-6 as the range I use. I try not to dose more because I like to keep things as close to the original tap water as possible to minimize (temporary) swings in water parameters for the fish during water changes as much as possible. That's just me though, and maybe that is an unnecessary caution on my part.

Have a good one, Jeremy
 

Tom Barr

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Yes, if you have soft water and low GH, adding 1-2 degrees using a Gh booster is plenty. Adding more is fine, but will not really give more growth.............so adding it is a bit wasteful I suppose.

Main thing is to not allow Ca/Mg to become limiting...........

Regards,
Tom Barr
 

calihawker

Junior Poster
Jan 7, 2008
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Tom Barr;29528 said:
The question is less about how low you can go and more about what is practical dosing for you personally, some do not mind daily dosing, some 3x a week, some weekly , some none at all:)
Yes, that really is the question. Things are working out very well right now dosing ferts daily and adding gh booster during water change. I'm going to try Jeremy's suggestion and us CaCl instead of CaS04. See how that goes.

You could add dolomite, that would dissolve fairly slow and add Ca/Mg.
Practical, easy, but not that precise.
I have a whole bag of dolomite that I used in a calcium reactor when my tank was reef:eek: I had wondered before if it would be possible to use one on a planted tank. Using a ph controller would make it more precise. Hmmm


Steve