What are Arcadia tubes? Are they compact flourescents? Do you know what their
wattage is?

Forgot to mention the tank is 260 litres.

What are the dimensions of the tank?

The problem is the water in my R/O vat, just can't seem
to get the pH at 6.8-7.0 with a KH of 3 or 4.

So this is not in the tank, no plants, no CO2 injection?

If so, then a KH of 3 or 4 should give you a pH of 7.4 or 7.6.

The "normal" CO2 level of water (no CO2 injection) is about 3ppm. So if you
look at Chuck's chart:

http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm

You should be able to find what a "normal" pH is for a given KH. Just look for
for your KH, then go acrcoss the row, looking for the box that gives you 2-3
ppm of CO2. That should be your normal, non-injected pH.

A pH of 8 is definitely a bit high for a KH of 3 or 4. If that's really the
reading you get, I'd say there's something wrong with one of your test kits --
or with the way you're conducting the test. :-) However, you can't expect to
get a pH of 6.8 or 7.0 either, without injecting CO2.




Leigh

http://www.fortunecity.com/lavender/halloween/881/