Rainwater should be good to go, so long as you control pests that come along for the trip.
If your tap water is hard with calcium and not sodium ... blend it down to an EC of 0.3. It's free cal-mag!
Blend it down with what?
Mix rainwater in with the tap water to achieve a reading of EC 0,2/0,3 ???
In the next few days I will assemble guttering to catch 'run off' and funnel it into a few large barrels.
A 100lt slimline Water Butt will be indoors (very close to my grow area)
and one (or two - depends on financial situation) 25lt rigid plastic 'Jerry' Cans and two (or three) 10lt buckets will allow water to be moved around AND nutrient solutions prepared for Ebb & Flow BEFORE it is poured into the reservoir.
In containers it is much easier to tweak and fine tune the final product.
EC too high....?
Add more water to dilute EC strength.
pH too low...?
10ml of pH UP in 500ml of tap water, mixed well.
Pour a little into nute solution, leave to rest for a few minutes.
Retest pH of nute solution.
The one thing that is free and dependable, in Northern England, is rain.
My household supply of tap water is on a meter so using an R O Unit to filter out the 0.5 EC could result in 4 litres being wasted for every 1 litre that is filtered - Or, to filter enough tap water to produce enough to fill my 140 litre reservoir, I'd waste 560 litres.
A ratio of 4 litres wasted for every 1 litre produced of suitable water (EC 0.2/0.3).
Rainwater is certainly the best way forward for my situation.
