I'm going to collect rain water for my tank (whats the betting it wont bloody rain).

[Marne]

So after having problems with high ph I am going to attempt to use rain water. My tap water ph is very high (around 7.8-8), I don't want to use treatment so thought I would try the rain water.

What do I need to do? do I need to filter it before using? I will test it first and collect it in a clean bucket.

Now preying for rain .

I wouldn't use rain water, it can contain all kinds of airborne pollutants, and anything on your roof if you collect it from a down pipe.

If you want to reduce your pH then using RO water (with added minerals) is the safest way. You'll also need to change the pH very gradually because sudden changes are bad for the fish.

7.8 isn't that high but you've said before that it was higher- do you know what is making it fluctuate?

I think the problem is just our tap water, at the moment my tank water is slightly lower than the tap water, cant remember the reading just that when I tested it it was dark purple (around 8 I think). Where do I get RO water from?

I havnt got a huge amount of fish at the moment, I want to get the ph sorted before getting more.

You can buy RO water from aquatic stores or you can buy your own unit. It's cheaper to choose fish that match your tap water although if your pH is fluctuating then RO is going to be safer. Really, your tap water pH shouldn't be fluctuating much if it's all coming from the same source. I think the best idea would be to just monitor the tap water pH over a period of time (leave it for 24 hrs before testing) and see what it's like.