# Rainwater question



## parotet (2 Apr 2015)

Hi all

I got a two questions for you. I have discovered near the family house in the countryside a small building that collects rainwater. I use tapwater for my largest tank but I am trying a mix of RO+(hard)tapwater in a small one. The 50% weekly WC is 7 liters, so I use just 3.5 liters of RO which I have to buy (0.1€/liter). 

This new finding opens the possibility of collecting once a month all the amount of water I need (at least during some months or after rainfall). Luckily we have a GH test kit (forgotten by the washing machine technician) and what surprises me is that it gives a result of 4dGH. Do you think it is rainwater with this value? I am not sure if it has been harden somehow in the concrete water tank (maybe limestone sand/rocks used). The tapwater (from the limestone aquifer) gives 14 dGH. I have my KH test at home. The RO water I buy at the LFS gives obviously 0dKH. Would this result be more important than GH?

The other question. The only thing I have for bringing the water home are plastic cans that were used for doing DIY ferts (comfrey+water) and mixing a mild organic fert (based on beetroot and manure with a nitrogen richness of 3%)... It has been dry for months. I can buy new ones these days but I have a few of them and I would prefer to recycle them. My guess is that a light wash with water and it will be ready to use, what do you think?

Jordi


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## dw1305 (2 Apr 2015)

Hi all,





parotet said:


> Do you think it is rainwater with this value?


Jordi, I think the value is quite likely to be correct for your rain-water. It is a fair bit wetter here than with you, but it is all limestone locally (Jurassic limestone, S. Cotswolds), and our rain-water varies between 30microS (in the winter after it has snowed) and ~150microS in the summer when it has been dry for a while. 

I haven't ever specifically looked at dGH/dKH, but I'd be confident that nearly all the conductivity is from limestone (and soil dust) washed out of the atmosphere and of the roof etc. 

cheers Darrel


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## tigertim (2 Apr 2015)

i use pure rainwater...ph7.5...kh3  gh5  with great results....the plants your keeping and fish more than likely will come from softwater areas 

after cleaning fill the cans with tap water....leave overnight n swill....they'll be fine imho


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## Lindy (2 Apr 2015)

My rain water is ph6 tds 2 gh0. I hadn't realised there was so much variation within rain water.


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## JohnC (2 Apr 2015)

my tap water is a private supply at the new house. currently has ph 6ish tds 33 gh/kh 0. having to buffer it a touch to add it to tanks. the tanks with mini landscape rock (which sends the kh/gh higher) have needed a little bit more careful water change of late. too much water shock for a couple of my more sensitive fish.


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## parotet (2 Apr 2015)

ldcgroomer said:


> My rain water is ph6 tds 2 gh0. I hadn't realised there was so much variation within rain water.


As Darell says, the limestone dust on the roof or in the air may be the origin of this 4dGH.... Not sure if you have ever been to East Spain but except for some small areas, the rest is a huge karst system (dissolution of limestones: water + co2 creates carbonic acid that dissolves CaCO3), thus a landscape dominated by sinkholes, caves, poljes, subterranean rivers.... It's like a huge sponge that unfortunately gives as a result very hard water with lots of Ca dissolved.

Jordi


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## Lindy (3 Apr 2015)

Sounds facinating. I'd love to see some subterranean rivers. Used to drive through to/from France from Gerona airport every year and stayed on the coast.


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## parotet (3 Apr 2015)

ldcgroomer said:


> Sounds facinating. I'd love to see some subterranean rivers. Used to drive through to/from France from Gerona airport every year and stayed on the coast.


It's very nice but the landscape looks quite dry... At least it is sunny!
I've been several times with some colleagues visiting caves with subterranean streams, really interesting from the biological point of view with several endemic species of insects restricted to certain caves' systems

Jordi


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## Lindy (3 Apr 2015)

We flew in to gerona once and drove to the coast thinking we'd stay a couple of nights before heading to france. Walked past dreadful stalls of cheap samurai swords and clothes and sat to have a coffee while we decided what to do. The final straw was the coffee arriving with spray can cream piled on top and covered with little sprinkles. We left right then. We have stayed in lloret de mar though. A hotel on the cliffs full of spanish and french holiday makers. Absolute bliss.


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## parotet (6 Apr 2015)

Hi all

I took a sample home to test parameters. I measured 3dKH and 4dGH, a bit harder than RO water but it looks I have managed to find good and free rainwater source in the dry Mediterranean (annual rainfall in the place where I collect it is just 500 mm). Not sure if it will be good enough during the whole year but it's great if I can use it at least during some months.
Thanks for your help.

Jordi


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## BigTom (6 Apr 2015)

Nice one. That's about the same sort of reading I get here in Cornwall. 

Sent from my Xperia T using Tapatalk


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