I just setup my first planted tank using a lot of information gleaned
from this newsgroup.

Setup:

Tank Size: 55 Gallons
Lighting: 2-55W CF lights from AH Supply
Substrate: 6 bags of Onyx Sand
Filter: Magnum 350 - using micron filter
Plants: TrueAquarium 55 Gal assortment - mostly one with low to
moderate lighting requirements
CO2: Carbo-Plus

Tap Water Quality: pH 7.6
kH 3
GH 3

Here's my problem ...

I setup everything in anticipation of the plants two days ahead, filled
the tank 3/4 full and to let the Onyx dust settle. I also dropped in a
handful of 'seeded' bioballs from my LFS to get a headstart on the
bacteria. Checked the water after the second day and saw that the kH
had crept up to 4 and the GH up to 4.5 - I assumed it was from the Onyx
- but I did not start the Carbo-Plus.

Added the plants last Thursday - nice selection and they arrived on time
in very good shape, topped off the tank, set the lights and Carbo-Plus
on timer to go on for 11 hours per day. I set the Carbo-Plus at 3 LED
bars.

Checked the water on Friday, expecting the pH to have gone down, but it
was still at 7.6 - upped the Carbo-Plus to 4 LED bars.

Checked the water on Saturday, still waiting for the pH to go down, but
it was still at 7.6. Also, checked Ammonia (just a trace) and Nitrite
(none).

Checked again last night - Still a pH of 7.6. Also, checked Ammonia
(none) and Nitrite (none). Picked up a Nitrate kit and tested at 5ppm.

Any clues to why there is no pH drop, hence no CO2 being added to the
water? I've checked the Carbo-Plus setup and it it installed
vertically, opposite end of the tank from the intake to the Magnum,
directed the return a little bit downwards to try to minimize surface
turbulence.

Any thoughts, suggestions or opinions welcomed.

Tim Louie

Any clues to why there is no pH drop, hence no CO2 being added to the
water?

Measure your KH, and use that to determine how much CO2 is in your water. With
Onyx as a substrate, you can't rely in pH changes to tell you your CO2 levels,
since it buffers the water.

Your tank is a bit on the large side, for a Carbo-Plus. Setting it at 4
probably won't be enough. Try 7 or 8 instead.

But first, get a KH test kit!


Leigh

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