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To much light?

Hello everybody.  I haven't contributed for some time but I have been 
reading the mail.  I have a problem and would appreciate some 

My setup:
I have a 55g, heavily planted tank.  I planted it on Dec. 6, 1996.  It 
is planted with easy plants; the easier crypts, H. Poly, dwarf 
swordplants, hair grass, V. Spiralis and B. Carolina.  The plants are 
healthy and growing.  My circulation/filtration system is a Rainbow 
"Quiet One" pump with two filters made from under sink water sediment
canisters.  The smaller uses the standard 11" long filter that I remake 
by opening and replacing the paper filter with Poly batting from 
WallMart's.  The other is the larger canister with three removable 
stackable containers make from 4" PVC pipe.  Right now I have one filled 
with ceramic beads, the second with aquarium filter lava rock and the
third for peat, charcoal or more lava rock.  I have the pump on the 
outboard side of the filters so I can inject my CO2 just before the pump 
impeller.  I have a "CO2 reactor" made from a 18" piece of 2 1/2 inch 
PVC filed with marbles hanging on the back of the tank.  The pH is very 
stable with this arrangement.  I set it for 6.8 to 7.0 and it just
doesn't vary.  The substrate was a mixture of unwashed river sand that 
had washed over some very rich bottomland, vermiculite, 16oz of 
laterite, with a layer of aquarium gravel covering it.

Water changes:  I religiously change 15g of water every two weeks and 
replace with water from a home RO unit.  I test the water and increase 
general hardness with Kent "RO Right" and carbonate hardness with CaCO3.  
Additional calcium as needed using Kent calcium chloride.

Lighting:  I have two shop light fixtures with the ballast replaced with 
electronic ballast.  The bulbs I've been using are the "Colortone" type 
warm white 40 W.  I have the two fixtures wired on separate timers so I 
can generate either 80W of light or 160W.  It can be adjusted to produce 
either a single setting of 80W for the desired length of time or two to 
three periods of mixed 80W and 160W output.  I use a covered top; I 
replaced the opaque "hinge" with a silicon sealer hinge and the opaque 
plastic with clear Lexan and lined the fixtures with chrome Monikote.  
I've tried removing the top but observed no variation in the aquarium
except an increase in evaporation.

Fish: 9 rainbowfish, 1 cardinal tetra, 1 small pleco and a
small algae eater.

Testing: Nitrate, Iron, carbonate hardness, calcium, alkalinity, general 
hardness, phosphate, pH

Test Kits: Iron, nitrate and alkalinity, LaMotte.  Carbonate and general 
hardness, Tetra.  Phosphate, several.  Calcium, several. pH, Bromothymol 

I have been using PMDD as recommended by the Conlin/Sears paper since 
planting the tank.  The PMDD uses Plantex CSM as a basis.  I have varied 
dosage to lower the iron level from the recommended .2PPM to as low as 
.05PPM with no visible effects on plant life within the aquarium (and no 
effects on the algae either).  General hardness is adjusted to be 10 to
12 degrees and carbonate hardness to 5 degrees.  The Tetra carbonate 
test and the LaMotte alkalinity test correlate well.  I maintain the 
nitrates at the recommended 5 to 10 PPM and calcium between 15 and 
30PPM.  The phosphate has never measured zero but normally registers 
between zero and the first step on the reference indicator.

The problem: I've always had more algae than I would like.  Up until a 
month ago I was delivering 12 hours of 160W of light to the tank each 
day.  Several months ago, the hair algae began to be a real nuisance.  I 
tried several approaches to trying to solve the problem.  I increased 
the CO2 until the pH had droped to 6.4; the fish became uncomfortable 
but the algae stayed.  I also tried adjusting the hardness downward by 
changing with unadjusted RO water but no effect.  Raising the hardness 
didn't work either.  By the way, these were gradual changes; I lost no 
fish or plants.  I tried using peat pellets in the top canister of the 
filter but outside of tea collored water, no effect.  Right now I have 
charcoal in the filter but I attribute the improvement with the 
reduction of light and not the charcoal.  When I went on vacation a 
month ago, A blanket of hair algae covered everything.  Plant growth had 
almost come to a standstill.  When I was preparing to leave, I decides 
to leave the light off and open the curtains.  Enough light to keep the 
fish happy but not near enough for photosynthesis.  My thought was "If I 
can't make it better, at least it won't get any worse while I am gone."  
When I returned 10 days later 70% to 80% of the algae was gone.  I had 
previously experimented with lowering the amount of light but my 
interpretation of the general consensus of members of this group was 
that the tank needed the 160W for 10 to 12 hours a day so I didn't even 
consider reducing it by one half.  For the past month, I have been 
running at 10 to 12 hours of 80W of light.  This seems to be the 
threshold for algae growth in my tank.  I have the lighting running at 8 
hours of 80W right now in an effort to reduce the remaining algae.  The 
dwarf swords are still being suffocated by the algae but it is shrinking 
at the light levels I am using.  The plants are again growing furiously 
but I am afraid that this is temporary at my present light levels.  

Recommendations, suggestions, ?: Again, the tank is nearly 20 months 
old.  Has problems but is reasonably healthy.  Looks fairly well right 
now but would look great if I can just get rid of a little more algae 
and keep it that way.  Question: how do I raise the light level without 
raising the algae level?

Thanks for listening.  Any help will be appreciated.

k5vkq at ix_netcom.com
"Always walking in the weeds"