Ro Calculations

[tomchurchman]

I'd like to use RO in both my tanks but this means about 75l per week for water changes, I can get it from the LFS (1 mile away) for £4 per 25l including minerals so:
3 x £4 = £12 per week
£12 x 52 weeks = £624 per year!
I'm on a water meter at home and would need to purchese both an RO unit, several stop valves and a water butt or two (£150?)
How do the two approaches compare financially. Waste water will be welcomed by my garden.

By the way my tanks are:
1 x 80l, mixed community, 30% planted
1 x 240l been set up for 2 months, heavily planted and aiming for a South American biotope, with Tetras, Corys, and Chichlids, possibly Discus in the future! (just a few Danios in there at the minute) My ideal Ph is therefore going to be around or below the 7 mark, my tap water is 7.5 and at the moment so is the tank. I'm using 2 yeast based Co2 systems joined together and have about 4kg of bogwood.
My tapwater contains a tiny bit of Ammonia (less than 0.6) and quite a bit of phosphate, cant remember how much but it was off the scale on the LFS nutrafin test card, also Nitrates at 10 - 15.
All comments welcomed
Tom

 

[OohFeeshy]

For the fish you're aiming for, and tap water, you shouldn't need to use 100% remineralised RO. There's a calculator on PFK ( http/www.practicalfishkeeping.co.uk/pfk/...rson_square.php ) which calculates required dilution of tap/RO for whatever hardness you want, I haven't used it so I'm not sure how well it works but it looks fair enough.

 

[dave_m13]

I use RO water on all my tanks purchased from LFS.

On 400 litre I use half tap and half RO water to fill 15l bucket, with the amount of wood and CO2 going into tank, the PH is around 6.6-6.8, just tap water is about 7.6. I only do this as I have Cardinal tetra and most of the other fish prefer softer water (not actually needed though). I get 2x25l containers refilled every 2 weeks for water changes, £5-£6 every 2 weeks.

In the 2 smaller tanks I use 100% RO, with wood and nutrafin CO2 on both, PH is 6 on one and 6.4 on the other at the moment as its new setup but pretty sure will reduce to 6 soon. 10l on each tank every week.

To be honest I have never thought about buying RO unit, buying RO from lfs is easy and gives me excuse to go to the lfs.

As mentioned you do not really need 100% RO, I suppose it depends on what you want to achieve and what hardness you want.