Gone mad with my new TDS Meter :)

[smithrc]

Right folks,

Just got home to find my TDS meter has arrived - I've been going mad with it and would like some feedback...

Tap water - 450 ppm
Rain water - 140 ppm
Condensed rainwater - 3 ppm

So - can i use rain water to lower the TDS in our breeding tanks (I've done 1 RO and 2 rainwater changes and the TDS in that tank is at 300 ppm)

If I left the lid on the water but on the skew and collected the evaporation - woudl that be ok to use?

All i'm trying to do is avoid RO - its £3.50 for 25l at our lfs (yep I know $$)
I have an RO unit in the garage that hasnt been used for about 1 year (but was still wet last time I checked) so it will probubly need a new membrane BUT we are on a water meter.

Is rainwater - or condensed water ok to use?

[smithrc]

LOL

Having just looked and our water suppliers site - it is only 102p for a cubic meter - thats about 220 uk gallons!!

ok so even factoring in the 5:1 waste... thats a rather scary 2.8p a gallon.
25l = 5.5uk gal = 15.4p

oh forgot to add the VAT - 18p for what the store charges £3.50p for!

so even at 7:1 its about 25p for a 25l drum!

[smithrc]

I set up the RO unit yesturday...
It had been sat for over a year - but after a flush through. It is still in perfect working order

TDS has been falling since it started running - It fell from 60ppm to 12 after the clean and flush and is now at 6ppm

I'll be using my own RO for the first water change tomorrow

[jerms55555]

Make sure you add some RO right by Kent to add the needed minerals that are taken out....I use RO right and discus essentials.....and I think it takes up the TDS by 20-40....

[smithrc]

I'll be mixing with the 'waste' to get to the desired TDS

Just need to check what I'm aiming at as I've got to bring the tank down from 300ppm (after a few RO/rain water changes already)

Aiming for about 50 I think