- [F] Yellowing plants, any suggestions?
by girard-at-ecs.umass.edu (2 Apr 92)
Date: 2 Apr 92
In the beginning of February, I set up 40+ gal freshwater tank
which was intended to be a heavily planted tank, modelled after
(sort of) some of the plant tanks described on the net.
Since I'm a poor grad student, I couldn't afford some of the
setups described here (MH, Dupla, etc, etc.), so I tried to find
economically but hopefully acceptable substitutes for my tank.
I did splurge and buy a 20# CO2 tank and regulator.
For lighting, I use two 4' shop lights, with two regular cool
white bulbs (4100K), a GE "full spectrum" plant light (pinkish),
and a GE Grolux plant bulb (evil purple). The lights are suspended
about 2-3" above the water surface (there is no cover glass).
For filtration, I use a DIY trickle filter (biological) with a
Magnum 350 (w/ micron filter) for the pump. With my setup, I'm
getting about 160 gal per hour flow rate. The CO2 is injected into the inflow hose for the Magnum (which is
downstream of the trickle filter), with 6-10 CO2 bubbles per second
(small bubbles, not from an airstone, but from a 1/16" ID tube).
Water pH = 6.8 - 7.0 steady
kH = 5 degrees (tetra tester)
GH = 3 degrees " "
NO3 = < 12 ppm " "
NO2, ammonia = 0
Substrate : 3.5 " clean gravel, uniform round particles about 1/8"
to 1/4" diameter over a mixture of 3# African violet potting soil
mixed with about a quart (dry) of peat moss mixed with 1.6 Kg of
laterite. This fertile "mud" forms a uniform layer about 1/2"
thick under all the gravel, and is presently full of roots (you
can see the bottom of the tank from inside the stand).
Occasionally, I dump in a generous squirt (2-4 times per week) of
iron supplement. This is commercial iron supplement for outdoor
plants, and is chelated iron with chelated trace elements (copper,
zinc, etc). It is made by a common fertilzer company, whose name
eludes me (bottle is opaque brown, the label is yellow, with red
markings). I've been using it for a few months, and it does
not appear to have any adverse effects on the fish.
The problem I'm having is that my plants aren't lushly green, but
a yellowish green. I'm fairly sure there is enough iron in the
water, but w/o a test kit, I can't be 100% sure. I am getting
plant growth, and I think there is enough light. Could the lack
of blue light inhibit chlorophyl production? (besides inhibiting
plant growth). Do I need to add more iron? I don't want to have
to buy $15/pint iron supplement if all I need to do is add much more
of the stuff I have. (If I do put alot, it makes the water sort of milky
(not too bad, though)). I know this is rather sketchy, but I don't have a
lot of time to go into details (class in 10 min...)
What could I be doing wrong? What can I improve? Any other
suggestions? criticisms? etc.
Oh, yeah, fishload is relatively light: 2 lace gouramis, 8 black
mollies, 6 red-eyed tetras, 2 swordtails, 2 siamese algae eaters, a
clown loach, 5 neons. Sorry, but I don't know the Latin names.