Hi there,
The other day a couple of people on facebook asked me about the suitability of rainwater for use in fish keeping.This is a really good subject to have a banter about because for years people have asked me this question and for the first time i will get to write something about it.
I am sure that a lot of people are thinking about collecting rainwater for use in the home aquaria and pond.Especially because of the impending water charges madness we are about to face.I do not think that it will be a simple as just collecting your own water do you really think that it will be?I read recently that in six states in the USA it is illegal to collect rain water?Did you know this?Well it is true it belongs to the government and if you are caught hoarding it you are in big trouble.I suppose the reason is lost revenue it is always about revenue and not morality.Now on the basis that every government is about revenue i can see this creep in in the near future trust me what happens in the states usually happens here too.
Okay that is my little rant over.Aquatic Village gives away water.We have an amazing spring so if any one wants soft water PH 6-6.5 come up n get it.
Right rainwater.Firstly water is a very very complicated beast.On the basis that you know the parameters you are looking for for your aquarium you are on the right path.The biggest problem with rain water is stability.Rainwater is the building block to water as we know it.As the water passes through the system ie to become groundwater this is where it gains its characteristics.If we use it straight from the sky we have an immediate stumbling block to overcome.Let us forget contamination for a moment and let us concentrate on the liquid itself.It is pure.Kh and gh non existent for argument sake even though some will argue i will argue back contamination.We have a water source that will have no fixed pH and is likely to crash or rise with the slightest stimulus.
Try vigorously aerating rainwater and see what happens chances are your ph reading will go off the chart in the alkaline direction.This can be catastrophic.Why? Easy half of you still don't know how or what a test kit is and you will dump rainwater straight into your fish then go online and blame the world instead of yourself.Here is a chance for me to reiterate but a test kit look after your own destiny any shop that test your water for you is not up too much it is called treating you like a mushroom.......
Anyway some rain will have a low ph depending on the amount of co2 in the atmosphere.Heavy populations ie towns and cities will result in low ph which is no good for alkaline fish.Again i will take the moment to stress that did you know that alkalosis or acidosis will produce the same symptoms as most of the fish disease we deal with???Well me awl pal they do.If you see your fish sitting on the aquarium substrate looking miserable check your ph.If you see mucus on your fish and it even turns white and stringy check your ph.......flashing and rubbing check nitrite and ph.
Back to rainwater.Rainwater is fine as long as it is collected in an inert container from an inert source.Check to make sure the tiles etc on the roof are inert and gutters etc are plastic......iron gutters is a no no iron in the water will interfere with the physiological workings of a fish and will prevent it from healing wounds etc.Zinc from galvanized gutters etc a big no no so be practical here.
So you have your rainwater now you will have to shape it to suit.Mineralization is usually the key.Give the water the capacity to buffer itself.We are using small amounts and i know what you are going to say out loud why doesn't rain mess up lakes and rivers.The key to that answer is in the previous line thank god i added this.Large volumes of water are inherently stable small volumes can be a problem.I have a river running through a piece of land not far from my shop.It is a wonderful clear little stream with plenty of fish and greenery i have thought about doing something with it for years.The ph is 7.And it is crystal clear and tasty.....yum but add an airstone and bang........ph skyrockets to 9 plus.Why is the river so healthy?Volume for one.Dilution is the other answer.And as the river moves further from the spring it will take up more permanent characteristics form co2 etc and mixing with other water sources.
If you want to use rainwater than condition it accordingly.There are conditioners out there even the RO conditioners will help trust me this is important improve the kh and gh and you will be able to gain control over ph.Rainwater is amazing in its own right because it is pure until it hits the ground from there on lies the problems.Do not use willy nilly check before and after for ph.
I hope this helps the people asking about rainwater draw your own conclusions remember common sense prevails.....if you get stuck the ask the questions.....you can always find updates on our facebook page.
cheers
Ian
www.aquatic-village.com 
