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Paul Sears note on oxidation and trace elements reminded me of a
question I asked a few months back that wasn't answered.<g>  I'm using
tap water in my planted aquariums.  We've got Chlorine and Chloramines
(sp?) in our water, so I use a water conditioner for changes.  The one I
use at present is "Prime" by SeaChem (for no other reason than it was
recommended by my LFS).  The label doesn't say what's in the bottle.  I
don't have the bottle in front of me, but I think it also talks about
"detoxifying" ammonia and maybe some other stuff.  Will the water
conditioners we use adversely affect the macro and trace elements we add
at water changes?  Thanks in advance.

Only 233 QYNGAs to go George! <g>

Next question:  Jeff Kropp and I were quite interested in dr. dave's
note the other day about CO2 levels, water movement and photosynthesis.
Neither Jeff nor I knew that "Ps" meant photosynthesis--so here's the
note again for those of you who may have been in the same boat:

"Research has shown that submerged aquatic macrophytes saturate their Ps
rates at about 30 mg/L [CO2]. At ambient CO2 concentrations (~ 1 mg/L),
Ps rates 
are typically 10 to 20% of max. A concentration of 15 mg/L will produce 
Ps rates somewhere between these two values. George Bowes states that," 
The major contributing factor to these high values [saturation at 30 
mg/L] is the diffusion resistance of water (Bowes. 1985. Pathways of CO2
fixation by aquatic organisms.)." This suggests that the optimal
for CO2 fertilization is to also increase the water movement within your

dave's follow-up note to Jeff:

"Sorry, Ps is short for photosynthesis. There is a layer of still water
surrounding plant leaves called the boundary layer or Prandtl boundary.
This is of significance for Ps since the rate of diffusion of CO2 in
is about 100000 times slower in water than in air. Decreasing the
of this layer will increase the movement of CO2 into aquatic plants and
increase the Ps rate. I mention this because authors frequently state
with CO2 injection the water must be absolutely still to avoid CO2
this is an inappropriate and self-defeating strategy."

Jeff and I have been wondering about how much water movement is
necessary to improve the CO2 diffusion rate.  Will gentle movement from
say, a typical canister filter return, provide sufficient movement?
Would we be likely to benefit from a powerhead "blowing" water in the
lower portion of the tank?  "100,000 times slower" diffusion rate in
water sounds like we're going to need a mighty force indeed!<g>  Any
practical advice here?

Since I'm on a roll, how about a 3rd question?  I've been practicing
"patience" with a green water problem in my 3 mo. old rainbow tank.
I've been testing to see if anything unusual is going on.  The biggest
surprise is nitrates.  Despite the fish load and the addition of 4-8
mg./l nitrate (from KNO3) at water changes, the nitrates drop to 0.0
(LaMotte) within a few days.   Other tank parameters:

40 gal. reg; pH 7.2 (mornings) ~7.4 (afternoons); GH 5; dKH 10
CO2 12-20 mg./l; phosphates - always 0.0 (Hach)
fish load: 6 boesmani rainbows (~ 3"); 6 ottos
plants: 85% planted with H. poly; E. tennellus; Limnophila; 
	Java moss; R. macranda; R. magenta, E. bhleri 
filter: 2213 Eheim with surface extractor
substrate: 3-4 in. of 2-3 mm sand; w/ dupla laterite (and 
	the root starter included in one box) in lower 1/3rd
water changes:  50% per week (recently 50% twice a week)
fertilizer: 5ml Tropica Mastergrow; 1/4 tsp KNO3; 1/4 tsp
	Epsom salts (at each water change)
lighting: 110 w compact fluorescent w/ 6700K bulbs--10-11 hrs/day
tank condition: in addition to the green water, it's been cycling 
	through various types of green algae with the H. poly and 
	E. tennellus taking the brunt of it; growth has been fast 
	after infested portions are removed

Any ideas?  I've been wondering if the lighting isn't too bright.  But
since several recent notes have commented that cf lighting doesn't
produce more light per watt, I should be okay at 2.75w/gal? Right?  My
LFS thought a "micron" filter pad would filter out the green algae (the
label said it would filter down to 10 microns in a canister).  I added
4 layers to the Eheim with no effect on the green water.

Thanks, Steve Dixon