# Cutting RO water



## Shamrock (17 Jul 2011)

My set up is as follows – Juwel Vision 180, Eheim 2324 thermofilter, JBL co2 unit. Amazonia as substrate. RO water. 

Just about to order plants and then I'll be ready to go.

I've read I will need to add some tap water to the RO water to put some minerals back in.

I need some advice on what percentage of tap water I need to 'cut' with the RO water when first adding water to the tank.

Or can I just start with RO water on its own.

What proportion is a good rule of thumb for any future water changes

I live in London and the  tap water here is very hard.

Thanks for any advice


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## SuperWen (17 Jul 2011)

It depends on how hard your tap water, and what water parameter do you want in your aquarium.
My case:
Tap water: pH 6.8 ; kH 13 ; gH 9 ; TDS 280 (not consistent, depend on weather)
RO water: pH 6 (initial) ; kH 0 ; gH 0-1 ; TDS 8
I mix 17 tap water : 100 RO water, and the result is: pH 7 ; kH 3-5 ; gH 3-5 ; TDS 60-80


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## hotweldfire (17 Jul 2011)

I also live in London. Do 50% water changes each week. 40% of the change is tap, 60% RO. Also inject co2 and use EI ferts. Parameters are - PH 6.5, KH 3, GH 7.


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## PeteA (18 Jul 2011)

Or use Topic ReMineral additive rather than cutting with tap water of unknown levels.


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## dw1305 (18 Jul 2011)

Hi all,
Depends on the water, I'd be quite happy to cut RO with my tap water, as it is low in nitrates, sodium etc but very carbonate rich (about 17dKH). I would expect PeteA's water would be similar, as he lives quite close to me and his tap water will be deep limestone aquifer water as well.

I would only use London water if I'd run it through an HMA filter first, this will remove most of the contaminants, but not effect the carbonate hardness. If you don't want to buy a re-mineralising agent, the DIY one here <http://www.theplantedtank.co.uk/RO.htm> will work out a lot cheaper over time.

cheers Darrel


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## Shamrock (18 Jul 2011)

Thanks for advice.

HMA ? EI farts ? KH? GH? additives ?  - completely confused now. 

All I want to do is grow some plants and keep some tetras.  My brain is fried with all the options.

Back to swot up some more on the net.


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## GHNelson (18 Jul 2011)

Hi
Yea it all can be a bit confusing....I live in Hemel Hempstead very hard water area,the ratio i previously used was 3 parts RO water to 1 part tap water.
Never had any problems...with that ratio.
hoggie


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