wrote:

TANK
i have a tank that is 48" (long)X 18"(wide)x24" (deep) = 90 gallons
base foot print 48"x18"=864 square inches
LIGHT
i have sofar bought a Compact Fluorescent 4x65watt (6700 k)total 260 watts
see below
http://www.esuweb.com/new_site/ccc_53116
i am hopeing that that is enought light.( 260watts / 90 = 2.88 watt per gal)

This is marginal to inadequate for your tank. I have a 24"deep 72 gallon
bowfront, which is the same depth but a bit smaller than your tank. 4x55w from
AHSupply, with their best bulbs and reflectors, is barely adequate for me.
Tricky substrate plants all fail, but above the substrate my plants tend to be
OK.

Remember, your tank is 24 inches deep. It's the depth that causes the problem.


SUBSTRATE

2x7kg (15.4 ibs) flourite= 14 kgs (30.8 lbs)
coverage recommended is 1kg (2lbs)per 31"sq
therfore 864/31=28 kg i have about half recommended amount
http://www.seachem.com/seachemframeset.html

also i have
3x5.4kg(12lbs) flora base=16.2kg they also recommed 2" deep
(and should ont be rinsed????)
http://www.redseafish.com/Product.as...D=33&proID=115

Sorry, you don't have enough substrate. I use 5 bags of Flourite in my tank, and
have barely 2inches, less in some places. I should put in another 2 bags. You
need more.

Regarding mixing with gravel, SOME people do it (not MOST people, by any means).
If you want to, be sure to use at least 50% Flourite, and pick a similar-sized
and shaped gravel. If the gravel is too large or small, the layers will
separate. If you can't find similar size, go a bit smaller rather than larger.

I was thinking of sloping gravel from back (high) to front (low)??

Works fine, but hard to maintain over time. Try it, you may be lucky.

Should i also add under gravel heater???

Most people who use them seem to be in high-altitude, low temperature places
like Colorado. Here in sunny California, they are not very popular.