From: jimh@ultra.com (Jim Hurley)
Subject: Re: Plant Tank Questions .... again ....
Organization: Ultra Network Technologies
Date: Fri, 17 Apr 92 17:48:13 GMT

In <1992Apr17.080310.8609@news.cso.uiuc.edu> erno@mrcnext.cso.uiuc.edu (Erno Pena) writes:

>First, thanks to George, Mark, and everyone else who sent me their collection  
>of Plant Tanks Articles. Because of that, I now have new questions.

>1. Would the Actinic Day fluorescent bulbs for marine reef tanks be  
>especially advantageous in a FW plant tank?

I always wondered about these bulbs. I mean to experiment with lights
sometime, but for the moment I just stick with Tritons mostly.
These bulbs are intensely blue, right? so you would need to add some
reddish lights as well. And then maybe a full spectrum light to make
color renditions normal (if that's what you want).

>2. What exactly constitutes a CO2 fertilizer system? As far as I can tell,  
>the absolute bare bones system include the CO2 bottle, a regulator with a  
>tank pressure gauge and a line pressure gauge, a fine control needle valve,  
>strong walled air tubing, and a bubble counter. For bare bones, the CO2 would  
>be injected into the intake of a cannister filter. For the more advanced  
>system, you would have a CO2 reactor in which the CO2 is injected. Do I have  
>this right? How much does all of this cost?

CO2 fertilization just means adding CO2 I think. The absolute simplest
way is to take a mason jar, invert it, fill it with CO2 gas, and let it
float in the tank or the sump. In my 100g tank I did this for about
a month. I had about 9 16 oz. mason jars in the sump. I'd fill them 
every morning (get's to be a drag after a week) and they'd last about
4 or 5 hours. That's plenty of CO2 - I see no substantial difference
now that I'm using constant CO2 fertilization.

My wife has a 27g plant tank - she takes a single mason jar and fills
it with CO2 on weekends as a supplementary fertilization. The plants
really enjoy that.

The jar will slowly sink as the gas dissolves, but it does that very gradually
and doesn't cause problems - it is possible, though, that a fish could get
trapped under the jar when it touches down.

The only problem with this approach (besides the chore itself), is that
there is no control over the pH. If you have low KH water like I do,
and don't adjust the hardness with calcium carbonate or baking soda
(for example), the pH will gradually drop while the CO2 dissolves and
then it will rise again when the CO2 is completely absorbed.

My tap is about pH 8.4, KH about 3.5. After it's been in the tank for a while
the pH settles to about 7.8. If I add CO2 this way, the pH lowers
about 1 pH per hour reaching equilibrium somewhere around 6.8.

The equilibrium point and rate depends on how much water passes under the
jar (the faster, the quicker CO2 will dissolve) and the KH.
When the CO2 is completely dissolved, the pH will start to rise again
as the CO2 gets used up and dissipates into the air. 

Some fish might not like this.

For the system you mention, you can remove all the chore work and keep the
pH fairly constant. The minimum automatic delivery system will
distribute tiny bubbles of CO2 into the tank at a slow rate.
The rate can be chosen so that the pH remains fairly constant.

CO2 dissolves 35 times faster in water than oxygen and you can get a
pretty good solution just by bubbling the CO2 through an airstone
in the bottom of a deep tank. This will waste a lot of CO2, but it's
not terribly expensive, and you could start with this.

Some means of containing the gas so that it is in contact with the
water for a longer period is more desirable. You could put some
glass jars above the airstone and capture the bubbles - similar to
the inverted jar idea. You could get a little more involved and
add a timer so the CO2 comes on for an hour/off an hour, etc.

Some people turn off the CO2 at night with their light timers -
here you have the pH swing problem again unless you adjust carbonate
hardness.

George Booth popularized the cannister filter reactor approach that I use.
You can add those CO2 bubbles into the inlet of a cannister filter
and let it mash around the bubbles for you. For me, I seem to get
nearly 100% of the injected CO2 to dissolve.

So here's a list of items you must have and some prices.
You could probably shop around and save a lot. I bought supplies
from a welder and connectors from a pipe and fitting distributor.
I hear home brewery dealers are also a good choice.

CO2 tank (depends on size) 10lb about $80, 20lb about $110.
   refills are about $10 (should last at least a few months)
regulator with tank pressure indicator $60 - $100
needle valve about $40
aircheck valve after the needle valve - a few dollars

You don't need a bubble counter, you can make an easy one by
stuffing the air check valve into the CO2 hose after the needle valve
and letting the hose fill with tank water.

You'll also need hosing and interconnects and a T section inlet for
the cannister filter, if you go that way.

The air check valve keeps water and pollutants from the tank from entering
the fine needle valve. If the cannister filter inlet is higher
than the air check valve, the CO2 hose will fill with tank
water and tou can easily see bubbles coming from the air check valve.

I do it this was, and use a brass air check valve I picked up
at a pet store. Sure, there's a little copper in there, but I do
frequent water changes, and I don't think it will hurt. Maybe
you can find a stainless steel air check valve.

>3. I had plans of mixing laterite, canadian peat moss, and rich dark topsoil  
>for the lower half of the substrate. After reading some of the articles, I'm  
>beginning to get the idea that the soil would leach extra nutrients into the  
>water and cause an algae bloom and even change the pH. Would adding soil to  
>the substrate really do this?

I wouldn't use topsoil. Too many pollutants, I think. Not just chemical
pollutants, either - biological as well. I would stick with
aquarium designated soil products to be safe. Perhaps if you
used topsoil and started with no fish for a while you can see what happens.

>4. Some of the articles sent to me mention getting chemicals from a  
>hydroponics supply house. Does anyone have experience with supplies from  
>there? Is it safe for aquariums? If so, please email or post the addresses  
>and phone numbers of some of the better companies.

What sort of chemicals? Fertilizers? Use as little fertilizer as possible.
Do without anything but CO2 for a while and see if the plants are
doing well. If the color is off - add some trace elements SPARINGLY.
I can't emphasize how much disaster you can cause if you follow
any dosage recommendations in those things. Avoid nitrates and
phosphate fertilizers unless there are no fish in the tank,
and even then be careful.

>5. Many recommended Delaware Aquatics and Mike T. as THE place to get plants  
>mail order. Is there anyone else?

I bought from him. If you look through FAMA you'll see others.
I think That Fish Place sells them. I buy most of mine from
local pet stores. It's a lot more expensive, but I get a chance to
see what they look like. Mike T. has been fair to me. He's also
happy to make recommendations and gab away for hours (it seems).
Watch out for snails and snail eggs.

>6. For a 30 gallon tank, would 2-36" bulbs provide enough lighting?

Sounds fine to me, but 48" bulbs might be easier to find and
cheaper.

CO2 fertilization is an expensive way to go for such a small tank.
It's better to have a lot of water to help buffer the pH shocks.

You'll have a lot more freedom in plant placement with a larger tank.



-- 
Jim Hurley --> jimh@ultra.com  ...!ames!ultra!jimh  (408) 922-0100
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