# Should I mix with rainwater



## Nigel95 (13 May 2017)

I ordered a gh test so will update later on that.

My tap water is:
KH 9
PH 7,5
GH 13
TDS ~170

Planning to have
30 ppm CO2
Monte Carlo
Dhg mini
Dragon stone
Amano shrimp
RCS
CRS
Rummy nose

My question is am I okay to just use tap water. Or should I add some rainwater to when doing water change. Should I top off with tap or rainwater?

I know rummy nose and rcs like lower Ph. I have aqua soil. Would the CO2 30ppm bump the Ph down to 6,5?


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## AverageWhiteBloke (14 May 2017)

Hello bud, you'll probably find when your GH test kit comes that it will be higher than your KH as GH is the total of kh+ the rest of the hardness. 
With a kh of 9 and 30ppm of co2 your ph should only get down as low as 7 according the the PH/KH scale. Obviously that doesn't take into account any other acids in the tank.
Mixing rain water would certainly help get the KH and TDS down and right now if you're in the UK rain water seems to be in short supply. So would benefit all round. Just be careful where you collect it from and bare in mind that if it hasn't been raining round your way for a while the first bit of rain will bring a fair amount of dirt down with it.  Some people bring the water up to room temp and aerate with an air stone before using it. Filtering over activated carbon is also beneficial at removing any pollutants in the rain water. 

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## Nigel95 (14 May 2017)

AverageWhiteBloke said:


> Hello bud, you'll probably find when your GH test kit comes that it will be higher than your KH as GH is the total of kh+ the rest of the hardness.
> With a kh of 9 and 30ppm of co2 your ph should only get down as low as 7 according the the PH/KH scale. Obviously that doesn't take into account any other acids in the tank.
> Mixing rain water would certainly help get the KH and TDS down and right now if you're in the UK rain water seems to be in short supply. So would benefit all round. Just be careful where you collect it from and bare in mind that if it hasn't been raining round your way for a while the first bit of rain will bring a fair amount of dirt down with it.  Some people bring the water up to room temp and aerate with an air stone before using it. Filtering over activated carbon is also beneficial at removing any pollutants in the rain water.
> 
> Sent from my STH100-2 using Tapatalk



Thanks for your reply. I live in The Netherlands the tds of my rain water is around 20. Filling my big tank with tap water is much easier than also using rain water. Maybe I should choose livestock that is more adaptable to my tap water . I do have aqua soil maybe it will lower the kh enough? Planning to do top offs with rain water.


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## AverageWhiteBloke (14 May 2017)

Yeah would make life easier to keep species that are suited to your tapwater although with your tds there isn't many that wouldn't be perfectly happy in that water. 

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## Nigel95 (14 May 2017)

I want rummy nose but idk if they will have their red heads in my water.


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## AverageWhiteBloke (15 May 2017)

They should be fine, prefer soft water but a lot of these will be captive bred specimens and are fairly hardy. My TDS is a lot higher than yours and I keep all the species apart from the rummy nose that you've listed.


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## Nigel95 (18 May 2017)

got the gh test and the gh from tap is 13.


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