I run RO water, 20p a litre at my LFS. Introduce it slowly to your tank though, drastically changing your water chemistry could be deadly to your live stock. A litre at a time with every waterchange, mixed with your fresh, dechlorinated tap water is the best method and slowly increase it til you have a 50/50 mix. Then, get a barrel, fill it with a 50/50 mix of RO and dechlorinated tap water, throw in a heater and an airstone and your set for waterchanges
I have been reducing the hardness of my water for several months now. Started at 134pmm and the water is down to 47ppm. I add a little more RO and a little less tap water each water change. You should keep a written record of your test results as you go. I use a TDS-3 pin meter to test for hardness. It is not expensive and I bought it off Amazon. It is very accuarte. I also use a PH-009 (I)A to test my PH level. When adding new fish I first but them in a bucket and slowly add RO water until the water in the bucket is close to the tank water before adding them. This will take several hours adding a little at a time to be safe.
Hardwater crew all say yo.
Hardwater crew say RO.
Say RO is the way to go.
The RO Rap by The Clown Lurch Crew. Available in all formats at all good music stores soon. Possibly.
You can get a small RO system for under £50 on Amazon in the U.K. Depending on how much youre gonna need it may be enough. Plumb it in outside so that the waste water is ran off into a container for garden use etc because they waste more than they RO and water metering will soon be compulsory in the U.K. You May already be on a meter thankfully we aren’t but will be this time next year.
It is fairly difficult for us to be advising how to soften this water when we do not have the important data on the water.
What is the GH, KH and pH of your source (tap) water? You may find this out from your municipal water authority, check their website. Or if you have the tests, give us the results. The GH and pH are the most important of the three.