RO water ratio etc question

[theonetruepath]

I have an auto-changing system set up. Mains water comes in via a reticulation timer (currently set to run for 5 minutes every hour). Goes through the two prefilters then through the RO filter. There is a bypass tap on the RO filter which I can set to adjust the ratio of RO to non-RO water.

When I set it so that there is 500ml per minute coming in, that gives about 60 litres per day (0.5 x 5 * 24) which is a reasonable amount to change. I estimate 60% RO water and 40% non-RO.

Overflow is via a standpipe in the back corner of the tank.

I measured the hardness of the water entering the tank, KH is 3 (50ppm) and GH is 5 (85ppm).

The question is, is this a reasonable RO ratio?

Also, I'm adding Aquasonic carbonate hardness generator so that I can add a reasonable amount of CO2 without going too acid. (I set the PH controller to 6.5). I'm also adding ferts which shouldn't affect hardness or PH or nitrate levels much.

Does this sound right, or should I be adding some other sorts of minerals to fix up what the RO filter is taking out?

Currently the GH in the tank is 8.5, KH is 6. The GH will drop gradually as the RO water replaces what's in the tank, I'll keep the KH at around 6.

Since I have all the gear to do pretty well whatever I want, what should I be aiming at (bearing in mind there are a lot of non-discus fish in the tank which would not like a PH of 5 and GH of 0)?

[ILLUSN]

Sounds good to me, wish i had that kind of gear in my fish room.

I'd lower the kh to 5, 3 is optimum but if your using co2 (like me) a bit higher is probably safer, ph is fine theres nothing wrong with discus at 6.5, thats the ph of my planted discus tank, you could always use hcl/ph down if ever you wanted to breed them anyway in a seperate tank.

I think your doing everything alright, put up some pics if you can.

[Ben]

sounds good, unless the water in WA is real crappy just the 2 stage filter would have been fine.