1. So I need to get a new one..question is how much are the new pumps costing at a pet store?
2. Also what are the benefits of a sump pump in a bigger tank.
3. Also how much weight can 2 by 4's hold that already has a 3 gal sitting on a heavy desk,a 10gal full of everything on a heavy dresser. It also has another heavy dresser by the window/ac unit.
4. put the 90 in between the desk and the dresser..would that be too much weight in the area between the heavy dresser ad the heavy desk?
5. Also I was thinking about using Flourish substrate and possibly eco complete with kitty litter mixed in since I already have the kitty litter.Also was just gonna use sand this time.
6. Also some ideas on some aquascaping would help too.I want it to be as natural looking as possible.
Lotsa questions entails a long response, here we go...
1. Sump pumps are expensive. A good one, as stated, might run you $100, and most pet stores don't sell them. You could find a decent underwater pump at a pond or pool supply store, but again be VERY careful about which you buy, as it might pump too fast or too slow based on the return rate (the rate of water being drawn down into the sump from the tank).
2. More water, easier access for things like water changes, chemical additions, etc., the ability to have a refugium/hospital/breeder compartment(s), MUCH better biological filtration if you do a wet/dry sump, and easier to keep obtrusive hardware like heaters, CO2 reactors, etc. out of the tank.
3. Not sure, but you mentioned the floor was cement and I'm pretty sure your tanks will be fine.
4. DO NOT DO THAT! Tanks need support all the way around or they will bend, bow, break, or ruin the furniture they're placed on, ESPECIALLY for such a huge tank!
5. You've gone all over the place with what you'd like to use as substrate, but only because there's so many choices. I would stay away from peat moss because a) you might have critters that dig it up, b) it doesn't do anything for the tank (in my experience), and c) it gets messy. Safe-T-Sorb is great; it's a clay material used to absorb oil spills in auto shops. I would either do a pool filter sand bottom with root tabs, or a STS bottom with no root tabs.
6. I like the reddish-black substrate look with some nice driftwood and live plants. Lace rock is nice too. I've found it aesthetically pleasing to build a cave in the middle, or prop things on the tank walls and leave the middle open. Also, whatever you plant, don't plant them too close together or their root systems will interfere and stunt their growth.
Lastly, pressurized CO2....
EXPENSIVE! But VERY efficient. I'd say a decent setup including CO2 cylinder will run you $200, but there's ways to slim it down.
Hope this helps...