# mix 50% rain water/ tap water ?



## eminor (9 Dec 2021)

hello, my tap water is KH 11-12, GH : 17, if i mix 50% of it with 50% of rain water, the kh will be 5 and the GH ~8, is it that simple ?  thx

i tried to do 80% rain water / 20% tap i think it's too soft for my red cherry, some are dying


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## Wookii (9 Dec 2021)

You calculation looks sound to me. 20% tap would give you about 3-4 GH, and that is a bit low for Neocaridina which generally are better with at least 5 GH depending on the composition. If your tap water GH is mainly or exclusively Ca (your water company's report may tell you), then you could cut it down to 25% and then bring the GH back up with some MgSO4 until you get the oft-quoted 3:1 mix (Ca:Mg). The only slight issue with cutting with tap water is the GH can vary through the year. 

Also make sure you still add a water conditioner though even though you are cutting the tap water.


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## eminor (9 Dec 2021)

Wookii said:


> You calculation looks sound to me. 20% tap would give you about 3-4 GH, and that is a bit low for Neocaridina which generally are better with at least 5 GH depending on the composition. If your tap water GH is mainly or exclusively Ca (your water company's report may tell you), then you could cut it down to 25% and then bring the GH back up with some MgSO4 until you get the oft-quoted 3:1 mix (Ca:Mg). The only slight issue with cutting with tap water is the GH can vary through the year.
> 
> Also make sure you still add a water conditioner though even though you are cutting the tap water.


my tap water is clearly full of Ca ( i live near UK in France =) )

The GH never vary at least not in the reports, so you think i should start mix 75% rain + 25% tap or can i go 50/50 right now ?


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## Wookii (9 Dec 2021)

eminor said:


> my tap water is clearly full of Ca ( i live near UK in France =) )



It would undoubtedly have Ca, but that wasn't the point, the point was whether it had any Mg. I live in the UK, much of the UK has very little Mg in the tap water, but in my region I have a fair bit in the tap water, so it just depends. For example if your tap water GH were 50:50 Ca:Mg, your approach to remineralisation and the proportion of rain water you might add will vary compared to if the GH was 100% Ca.



eminor said:


> The GH never vary at least not in the reports, so you think i should start mix 75% rain + 25% tap or can i go 50/50 right now ?



It may not vary, but the reports typically only give an average. My tap water TDS for example can vary from around 250ppm to 350ppm at different points in the year.

I guess the overriding question though is why you are looking to reduce hardness anyway? if it is to save on water, then that's fine, but that aside your shrimp and plants should be fine in your tap water anyway as it is. If you are looking to plant soft water specific plants, then halving the KH likely won't make the water soft enough anyway.


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## eminor (9 Dec 2021)

Wookii said:


> It would undoubtedly have Ca, but that wasn't the point, the point was whether it had any Mg. I live in the UK, much of the UK has very little Mg in the tap water, but in my region I have a fair bit in the tap water, so it just depends. if your tap water GH is 50:50 Ca:Mg, your approach to remineralisation and the proportion of rain water you might add will vary compared to if the GH was 100% Ca.
> 
> 
> 
> ...


the report say Ca 119 ppm, Mg : 1 ppm per liter, GH vary from GH 15 to 18 over the year, ppm is always near 240 ppm everytime i test it.

i want to reduce first to save water and then for cabomba furcata, myriophyllum red, and blood vomit plant, soft plant in a nutshell, i've seen absolutly no difference in other plant switching from hard to soft water though


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## Wookii (9 Dec 2021)

eminor said:


> the report say Ca 119 ppm, Mg : 1 ppm per liter, GH vary from GH 15 to 18 over the year, ppm is always near 240 ppm everytime i test it.



OK, we can call that zero MG for all intents and purposes then lol - though it is surprising that the TDS is so low for KH 12 + GH 17? (Edit: Just done the maths - 17.8ppm ~ 1dGH, so 120ppm ~ 6.75dGH - I'm not sure what else could contribute to a GH of 15-18? (perhaps @dw1305 knows?)

In that case you could do as I suggested above and cut with 20-25% tap water and bump the GH up with some Mg.



eminor said:


> i want to reduce first to save water and then for cabomba furcata, myriophyllum red, and blood vomit plant, soft plant in a nutshell, i've seen absolutly no difference in other plant switching from hard to soft water though



The first two should be fine with your cut tap water, but the Blood Vomit requires very soft water.

If I were you, and if you have a ready supply of rain water, I'd be tempted to use 5-10% tap water to get your KH down to 1 or slightly below, and then remineralise with MGSO4 and CaCl2 (if you want to use DIY salts) or Salty Shrimp (if you want to use an off the shelf product) to bring the GH back up to around 5. Then your low KH should ensure you can grow almost any softwater plant you want to.


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## eminor (9 Dec 2021)

Wookii said:


> OK, we can call that zero MG for all intents and purposes then lol - though it is surprising that the TDS is so low for KH 12 + GH 17? (Edit: Just done the maths - 17.8ppm ~ 1gGH, so 120ppm ~ 6.75dGH - I'm not sure what else could contribute to a GH of 15-18? (perhaps @dw1305 knows?)
> 
> In that case you could do as I suggested above and cut with 20-25% tap water and bump the GH up with some Mg.
> 
> ...


thx, i actually dose mgs04 using EI, i add 2.5 dGH a week, i'll double it, i don't have Ca in dry salt thought, i don't know how much is necessary :/


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## dw1305 (9 Dec 2021)

Hi all, 


eminor said:


> i don't have Ca in dry salt though, i don't know how much is necessary


Just use the tap water, it will supply the <"ratio of 1dGH : 1dKH">. I use a <"conductivity datum">, rather than adding a set amount of water.


eminor said:


> the report say Ca 119 ppm, Mg : 1 ppm per liter, GH vary from GH 15 to 18 over the year, ppm is always near 240 ppm everytime i test it.


You know that you don't have much magnesium (Mg), so the source of the calcium (Ca) in your water is from the <"dissolution of limestone (CaCO3)">.   

cheers Darrel


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## Wookii (9 Dec 2021)

eminor said:


> thx, i actually dose mgs04 using EI, i add 2.5 dGH a week, i'll double it, i don't have Ca in dry salt thought, i don't know how much is necessary :/



You probably don't need to add any more Mg. Ca is easiest using Calcium Chloride as is dissolves very easily and is readily available. Basically if you add roughly the same dry weight in Calcium Chloride (CaCl2) as you do in MgSO4 (Magnesium Sulphate), it comes out roughly in the desired 3:1 ratio Ca:Mg. If that pushes the GH too high for what you want, then just reduce both salts by the same amount until you hit the target GH.

For remineralising my RO water, I mix 117gr/L of MgSO4 and 127gr/L of CaCl2 with RO water (in separate 2500ml containers) which gives a 3:1 ratio of Ca to Mg.

I dose 20ml of each to around 25 litres of RO, which results in around 6dGH. So to extrapolate, thats 0.068g CaCL2 and 0.062g MgSO4 to get 1dGH in 10 litres of RO water in a 3:1 ratio 😅


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## foxfish (9 Dec 2021)

Eminor, where exactly do you live in France ?


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## erwin123 (9 Dec 2021)

eminor said:


> the report say Ca 119 ppm, Mg : 1 ppm per liter, GH vary from GH 15 to 18 over the year, ppm is always near 240 ppm everytime i test it.
> 
> i want to reduce first to save water and then for cabomba furcata, myriophyllum red, and blood vomit plant, soft plant in a nutshell, i've seen absolutly no difference in other plant switching from hard to soft water though


its really cool that you are trying to grow some of the more difficult plants in the hobby. you should start a journal and share your experience. I'm very interested to know from someone who is growing them side by side whether Furcata or Tuberculatum is more difficult, and tips for growing them.

Besides blood vomit (not an Erio I know), are you planning to pick up some of the rarer Erios for your tank?

p.s. you have posted photos of you tuberculatum elsewhere, but I haven't seen your Furcata yet.. can you post photos?


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## eminor (9 Dec 2021)

foxfish said:


> Eminor, where exactly do you live in France ?


thx guys, town name : Calais


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## eminor (9 Dec 2021)

erwin123 said:


> its really cool that you are trying to grow some of the more difficult plants in the hobby. you should start a journal and share your experience. I'm very interested to know from someone who is growing them side by side whether Furcata or Tuberculatum is more difficult, and tips for growing them.
> 
> Besides blood vomit (not an Erio I know), are you planning to pick up some of the rarer Erios for your tank?
> 
> p.s. you have posted photos of you tuberculatum elsewhere, but I haven't seen your Furcata yet.. can you post photos?


my furcata is going to move because she loves tonof light, she's almost die but i don't give up i alaways liked difficulty. sure i will try every hardest plant =)

the myriophyllum developped new shoots since i increased the light, 2*24w t5ho @ 25cm, near 150 PAR, any mistake and the algae going to be happy, i think that i have some diatoms. BBA seems to be dead since i use inline atomizer










the reineckii also developped insane red new leaves since i increased the light




there is the bulbs, 3000K + pink which seems to be high kelvin temp










the pogostemon stallata seems to love the amount of light, it gets really pink now =)




still there is dead algae or diatoms on lower leaves





there is test plant spot which i cant determine the species










At least there is a plant which seems so happy there, ammania senega...




really sorry about the quality


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## erwin123 (10 Dec 2021)

thanks for the pics, I find its useful to take pics every week to monitor progress of the plants.

the challenge is always the lower leaves - even if the new leaves look nice, always check whether the lower leaves are also healthy.

Ammannia Senegelansis is a reddish-pink plant - not sure why yours is so yellow, could it be a different species?


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## eminor (10 Dec 2021)

erwin123 said:


> thanks for the pics, I find its useful to take pics every week to monitor progress of the plants.
> 
> the challenge is always the lower leaves - even if the new leaves look nice, always check whether the lower leaves are also healthy.
> 
> Ammannia Senegelansis is a reddish-pink plant - not sure why yours is so yellow, could it be a different species?


i don't know it's been a week since she's there maybe it will eventually turn red


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