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TDS and GH

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Hi all,


This is my first post but hopefully somebody can shed some light


My tap water has a TDS of 99 and GH of 5


Now in my CRS tank the TDS goes down to around 65 and GH stays at 5

This tank has Aquasoil in


Is it possible to raise the TDS as this is very low and keep the GH as is?

and if so please help with suggestions



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Maurice. I answered this elsewhere a few times in the forum but it's helpful to understand.

gH is calcium carbonate. Each degree of hardness is also 17.9ppm. If you use an API test kit it measures 5 degrees that's actually 5*17.9 is 89 ish of math is right. So a TDS of 99 means your water is mostly carbonate because 89ppm or 5 degrees, the rest could be anything.

TDS is a measure of inorganics. Calcium, magnesium, salts, ions etc. take RO water and put salt in it. Your TDS will skyrocket where as your hardness will be zero. Sodium is not calcium if that makes sense.

So I cannot comment on Mosura but it's been commented many times - just get an RO unit. I got one for less than 75 on Amazon. This gives you pure nothing to build appropriate ions needed for shrimp.

Again nothing on Mosura don't know it at all. I could put a bottle of salt water together sell it to you and call it TDS up and you would be happy till your shrimp died. I'm sure TDS up works as intended but how does it help replace or alter the ions your water is blessed or cursed with.

RO unit and shrimp reminerlizsr is great water

Hope that all makes sense.

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Hi Roborep1,


Thanks very much for your in-depth explanation!

It makes very much sense yes.


Going slightly off topic here, but do anybody know anything about seachem aquavitro mineralise GH?

I know it is actually made for a planted tank, but unfortunately we here in Africa are very behind with shrimp keeping and breeding as a hobby, so we dont have any, and I mean any products for shrimp.


I will be ordering some Salty Shrimp GH soon from Han, but up till then I need something to harden my water.


Can I use this product in the meantime or is it a no go?


Any guidance or info will be much appreciated


This is what Seachem say on their website:



  • blend of divalent salts designed to restore or increase general hardness.
  • standard dose raises GH by 1 meq/L (2.8 dGH)
  • Description

    General hardness is the divalent metal cation content of the water. In most water this is comprised primarily of calcium and magnesium. Soft water has a low concentration of dissolved divalent cations, hard water a high concentration.

    The native environment of some plants (Cryptocoryne, Aponogeton, etc.) is soft, whereas others (Sagittaria subulata, Riccia fluitans, etc.) are more acclimated to hard water. In order to replicate these environments it may be necessary to adjust hardness.

    mineralizeâ„¢ is a blend of divalent salts designed to restore or increase general hardness.


    To raise mineral content/general hardness (GH) by 1 meq/L (2.8dH), use one inner capful (7 mL) for every 15 US gallons (56 L) when setting up an aquarium or when making water changes (add to new water). Thereafter, use once a week (or as needed). This dose raises GH by 1 meq/L (2.8 dGH). Target a lower general hardness for soft water, a higher value for hard water. Target a lower general hardness for soft water, a higher value for hard water.

    Note: The aquavitro cap offers multiple dosing solutions depending on the size of your system. Each inner cap thread is approximately 2 mL. The inner cap contains 7 mL, while the outer ring contains 28 mL (35 mL when both are filled to the level of the inner cap.) When filled to the top, the cap contains 49 mL.

    For reference purposes, water hardness is classified as follows:

  • Guaranteed Analysis:

  • Calcium(min)       13.5%

  • Magnesium(min)  1.2%

  • Ingredients: Calcium Chloride, Calcium Gluconate, Magnesium Chloride.

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Oh boy I think I was tired last night. Let me correct something.

dKH is carbonate hardness or calcium. dGH is typically calcium and magnesium. Both are one degree per 17.9 ppm.

You make no mention of your kH?

That product looks fine it will raise gH and kH. Some planted tank stuff has copper ions which are no good.

One other thought is perhaps being behind the times in Africa represents an opportunity for you.

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