# Measuring GH by using TDS?



## Puddles (Jan 5, 2013)

My gH liquid API test is a little old and I'm getting wonky results. I'm trying to figure out if it is my testing or my remineralizer that has changed. I measure 8 when I use the drops. This is pure RO water with only my gH booster added to it (Salty Shrimp brand) and I am getting a tds of 156. I can't find a conversion chart anywhere, just ranges. 

Can I use my TDS reading to tell my gH?


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## wicca27 (May 3, 2009)

not really. gh is just one thing that makes up TDS (told dissolved solids). tds is a combo of the hardness and all the stuff in your water from decaying plant mater and animal wast.


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## xmas_one (Feb 5, 2010)

Don't quote me but I'm pretty sure SS will increase your TDS 20 ppm for each degree of gh.


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## Higher Thinking (Mar 16, 2011)

Well each degree of hardness is 17.85 ppm. While testing with a tds pen will give you an approximate gh, it won't be specific because no gh booster adds pure gh. There is various levels of additives. Salty's has been known to be one of the more clean boosters so one would expect tds of around 20 per gh. You will have to test the tds and use an gh tester in order to get the exact tds/gh ratio.


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## TheDrake (Jul 18, 2012)

Most TDS meters really just measure conductivity, the amount of ions (charged particles) in solution. This isn't really TDS at all, but based on some generic assumptions, the conductivity number is converted into something approximating TDS, but it is all based entirely on measuring conductivity. Presumably your GH booster contains calcium and magnesium, which should raise both the GH and conductivity directly and linearly. If all else stays the same, you can add GH booster until you get the desired GH (using a non-expired GH kit), measure the conductivity (with your TDS meter) at that GH, and just use conductivity as your metric from there on out. If the concentration of the GH booster is constant from bottle to bottle, you shouldn't even have to do that; the amount of GH booster you have to add to your RO water to achieve a given GH should be about the same each time. Of course, as your RO membrane ages, the conductivity of your product water will gradually rise (possibly from Ca and Mg, but possibly also from Na, Fe, etc. which do not contribute to GH), but you should be monitoring that (via conductivity) independently anyway.


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## MABJ (Mar 30, 2012)

If you're using inert substrate, a clean remineralizer. (Salty is most reasonably priced, but Shirakura is the cleanest) You can test your GH roughly based on your TDS.


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## oblongshrimp (Jul 26, 2006)

Based on my GH test I was seeing about 15-20TDS per 1GH when using Salty Shrimp GH+. I was mixing it in a big drum with 100% RO water so there wasn't anything other than Salty Shrimp GH+ in the water.


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## h4n (Jan 4, 2006)

oblongshrimp said:


> Based on my GH test I was seeing about 15-20TDS per 1GH when using Salty Shrimp GH+. I was mixing it in a big drum with 100% RO water so there wasn't anything other than Salty Shrimp GH+ in the water.


same here!


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## Soothing Shrimp (Nov 9, 2011)

+1 to 15-20 TDS per 1 GH via SS


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## brandon429 (Mar 29, 2003)

hey Im going to piggy back on this as a new cherry shrimp keeper/breeder

for my long term planted tank which was just guppies for 12 yrs before being a shrimp tank, all i did for the water when i did bother to change it was take a five gallon bottle of ro di, fill it up 80%, then fill the other 20% up with dechlor tap which from my area is a butt load of calcium and magnesium salts. ph about 8.0 out of the tap. 

so I never tested any params for this tank, they are berrying up purchased not berried and no deaths after a month, think this semi soft general guess water chemistry is ok? long term...

its not causing cholorosis in the plants or snails aren't having chipped shells, they gettin calcium from somewhere imo. im judging shrimp shell integrity off the snails that have been in there a decade, Im thinking no dissolution means there are some ions for the taking. how dang specific do I have to be with gh kh on fw cherry shrimp for true long term health and viability. guppies are removed its shrimp only now, dedicated baby tank. 12 yr biofilm before entry they are real happy lol temp is 68 constant from oct-march and about 75 the other months. my plan is cherries only for now not really crs


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## oblongshrimp (Jul 26, 2006)

If your shrimp are breeding and happy I wouldn't bother messing with it.


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## acitydweller (Dec 28, 2011)

different gh boosters will raise TDS at varying degrees. It may be passable if you are sticking with one brand and know the expected TDS at the desired gh level...

However, performing a GH test is best.


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## randyl (Feb 1, 2012)

+1 on ~20 ppm per dGH when using SS and RO, it holds true for almost everyone using SS that I know of. 

I don't test GH in the new water for WC anymore, I just measure TDS 90-95 and use it. And the TDS in my tank maintains at around 100-110 steady. (GH is 5-6).


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