Re: driftwood & pH (cheesey lil' CO2 reactor)

> I haven't been able to get my pH
>down even after bubbling CO2 into the return line from my filter.

You probably are not maintaining sufficient gas-water surface exchange area.

Here's a simple reactor that works great. This is a repeat of an earlier
posting with some additional comments. (the biowheel has since been removed
- plants get all the nitrates,)

I've got a 29 with a Penguin 160 biowheel filter and faced the problem of
how to inject C02 without adding a power head. Since the filter element is
vertical, bubbles won't lodge under it so simple direct inlet injection
would be inefficient.

The design goal was to present a large CO2 surface area to a turbulent
water flow. This is done with a box placed on the inlet to the filter. The
filter inlet is extended a little over halfway into the box and holes are
drilled on bottom of  box at the ends. Water enters the box at the ends and
is drawn to the middle where it flows into the filter inlet. The CO2 forms
a large bubble which covers the top of the box. This bubble is exposed to
the rapid and turbulent flow in the box.

The reactor was fabricated from a 5"L x 1"H x 1.5"W clear plastic box.
First drill a hole in the bottom of the box to accept a short piece of
rigid 3/4" plastic tube, then insert the tube about 1/2" into the box and
glue it in place. Drill a hole on the end of the box and glue a short piece
of rigid 3/16" tubing for the C02 injection. In the top of the box at both
ends, drill lots of 1/16" inch holes. Now turn the whole thing over and
slip the 3/4" plastic tube sticking out of the bottom of the box on the
inlet to the filter and connect aquarium airline from the CO2 generator to
the CO2 inlet.

          connect to pump inlet
                |    |
                |    |
                |    |
                |    |
________________|    |_________________
|     CO2       |    |     CO2        |
|wwwwwwwwwwwwwww|    |wwwwwwwwwwwwwwww|
|               |    |                |
|   water                 water      ====== CO2 inlet
|_ _ _ _ _____________________ _ _ _ _|
 water inlet               water inlet

There are two minor design problems with engineering prototype 1:

1. The water inlet holes are too small and look like they might be prone to
plugging. My planned solution is to use a couple of the cylindrical intake
strainers like the one supplied with the pump. These are much less likely
to be plugged by a large flat leaf.

2: The box needs to be bit taller as the water surging in from the inlet
surges to the top at the box ends, thereby reducing the CO2 diffusion area.

My recent notes:

Actually, after drilling holes, in the lower side ends of the box, the flow
was much improved. I reccomend the end holes or attaching cylindrical
intakes to the ends, as this gets a flat high velocity sheet of water
flowing to the uptake with minimal "pinching" of the bubble.