Chris, i will try to respond to the questions/issues in your three earlier posts.
First, light. What do you mean by "Deep Blue" twin T5? Be specific please. This does not sound good for a planted tank, but I will wait until I know more before continuing (or changing my view).
S|substrate: unless you want a specific "iron" clay look, don't get the red Eco-complete. CarribSea make two substrates in this line, Eco-complete Black and Eco-complete red. As far as I know they are identical except in colour. Black is fine for a planted tank, ideal actually. Red will work but it will make a very different tank appearance, and unless you are after a biotope effect (replicating a SE Asian iron-substrate stream) i would avoid it. Get the black.
Cichlid pair: make sure you know exactly the species. This could be a disaster. Always, please, always research a fish before acquiring (or agreeing to take) a fish. Not all fish are "compatible" and I mean more than just behaviour. Compatible means they share identical needs respecting light, plant types, filter flow, substrate, water parameters, environment (rock, wood...)--and they must be well behaved.
A community tank has to be well thought out from square one in order to have not just a beautiful display but one that has healthy fish. All the things i mentioned above can cause stress, and that weakens a fish's immune system which makes it more susceptible to disease and probably results in a much shorter lifespan.
Twig catfish: You still haven't told me the species [one is in our profiles, is that it? Or is it a large "Royal" type?] so this is difficult to answer. I have a trio of Farlowella vittata that have spawned several times and I have successfully raised a few of the fry. If this is your fish [as the one in the profile] it does not need currents; mine seldom remain close to the spraybar, except when they spawn, they have always laid the eggs just under it. It does like plants and wood over which it will spend all day grazing algae. It will learn to feed from sinking foods (tablets, disks, pellets). It does not like any change to its environment, so it needs stable water conditions. And don't move it to another tank unnecessarily, this it certainly does not appreciate. Wait until the new 75g is well established, then move it. Mine always go into withdrawal for several days after being moved; I've only done it twice, due to moving the tank.
There is no benefit to airstones in a planted tank, and they are detrimental during daylight. At night is fine, but again, there is no benefit so why bother? Provided the tank is not overstocked, there will never be an oxygen shortage with live plants and a balanced fish load.
Excel was mentioned; this is something i would not advise. A|dding carbon sets up a higher level of balance, which means light and the other nutrients have to be increased. Keep it simple, there is less to go wrong and nature is better able to manage things anyway.