2 100 watt heaters would do the job. I had a 200watt heater stick on and it almost cooked my 155g. I use two 100 watt heaters in a 120g and they maintain the temps fine.So, I finally got my 75 gallon tank! Of course, now I have to stock it with equipment before my mbuna.
You experts out there, feel free to critique my ideas.
First, I am think'n of using 2 ViaAqua 200 heaters. Our house is often quite cool at about 19 degrees this time of year. I'm a little worried about a heater failing and having it cook my fish, after all the ones I've been reading about lately! But I'm thinking these aren't overpowered enough to do that? Or would they have auto shut offs anyway?
Next, I'm thinking of using a big old AC 110 HOB as my main filter, with a Max #3 prefilter attached to help it. As the fish get larger, I'd maybe add a second HOB. My stand probably won't have room for a canister at only about 15" high.
I'm also thinking of installing a drip system, for water changing. Then a drain to keep the tank at a constant level, either with a drilled, bulkhead near the top of the tank. Or a overflow box to take out the extra water. Does anyone know if Top Fin tanks can be drilled?
Now for my crazy idea, don't laugh! I'm seriously thinking of setting up a reverse flow UGF! To help keep the gravel clear, not as a filter system itself. I'd maybe power it with 2 Rio 1100s with each a prefilter attached again. This way, they'll push filtered water down, under the Lee Premium UGF, up through the gravel. Hopefully, keeping the muck from settling in the gravel substrate, and allowing the three, prefilters, and the HOB filter to take care of it.
The gravel I'd use would have to be more course than usual, I'm think'n. Probably about 1/2"- 1" in diameter and spread quite evenly to keep the water coming up from going to the easy, thinner areas. But this would also keep the mbuna from digging huge holes down to the bottom, which I don't really care for. I know, you're say'n they like to and have to dig. But I've seen plenty of vids of Malawi lake and there are huge areas inhabited by mbuna that have nothing but rocks and boulders, noth'n for them to dig. So I think they'll be just fine.
So, if my theory works, this should cut down on some maintenance!
A drip system is the best thing you can do to reduce maintenance. All of my tanks are on drip systems. Some are drilled, others use commercial overflow boxes, and some home built PVC overflows. I haven't had problems with any of the options.
If you don't mind the look of sand, it's less work than gravel. A sand or fairly fine Aragonite (good for cichlids) bottom, with a couple power heads leads to zero substrate maintenance. The waste sits on top of the sand and eventually works it way into the filter. If the sand is deep enough (2" or so), the mbuna won't be able to expose the glass bottom as it keeps raveling into the hole.