Rain water isn't scarce in England but...

[BedScien]

Can I use it for my brackish tank with figure eights in.

I have a barrel which runs from the gutter around my shed, both are plastic.

I've measured the pH and it came up as 6 - 6.5

And I've measured the nitrates and they have come up 0 or maybe 0.5

I will continue to do more tests on the tank water and some tap water to compare but what do you all think?

Anyone tried something similar?

[eieio]

I think I'd shy away from it............
it may be too soft, being rainwater (check the GH & KH)
also, it may have contaminants from whatever the rainwater washed off of your roof, which there is no reasonable way to test for

[G S P Freak]

I wouldn't trust it! Like eieio said, too many unknowns that could be in the water... Save it for watering your lawn! Tapwater with prime is a safer bet!
Also your rainwater seems pretty acidic, f8s love ph of the basic spectrum; 7.5-8. Your rainwater is actually more basic then most rainwater (5.2-5.5) but I'm betting you're tap is better (for many reasons besides just ph)

[Iliveinazoo]

I used to use rainwater for my figure 8's for around a 2 year period because my tap water has high nitrate but I don't use it anymore simply because it's easier for me to use tap water. I still have to add nitrate to the water to keep my plants healthy so I supposed that the nitrate in the tap may not be as high as the test kits would lead me to believe...

EDIT: For what it's worh I noticed no issues during the time that I used rainwater.

[RTR]

IMHO, no F-8 or GSP should be in straight rainwater. The GH needs to be significantly higher and as stable as possible. The rainwater collection surface and the plastic catch barrel must be fish safe. Not all plastics are safe.

[Iliveinazoo]

IMHO, no F-8 or GSP should be in straight rainwater. The GH needs to be significantly higher and as stable as possible. The rainwater collection surface and the plastic catch barrel must be fish safe. Not all plastics are safe.

RTR: Are you not hardening and remineralising the rainwater by the addition of marine salt and the aragonite/coral sand that is already buffering the water in the aquarium?

[BedScien]

I'll see if i can find out what plastic is used in the rain barrels. I would be surprised if it leached any chemicals into the water as they are made for very for long term use in gardens

[RTR]

Bertie: Yup, I would, along with the KH (which the aragonite substrate will help buffer as well). Our tap water here was for years from a very old aquifer and only slightly to moderately hard. A few years back, the local system had to add a well to supplement the total available water, and it is from a shallower and much younger aquifer, so not quite as pure and stable as the old system was, but the system now is much better operated. It is a trade-off, but overall a good one even if rather costly for the residents here. We are much happier with the system now than before. I do still collect rainwater for the deck plants We have non-trivial decks and lots of tropicals in the summer. But the tanks are all just tap water now. If water mods are needed, it is done during the minimum 48 hour tempering I give all my top-up and change water. I am still compulsive. That will likely never change. But I do run fewer specialized water tank now than I used to have going.