First off its probably a good idea to mention infos for this future tank.
So this will be a freshwater tank, I plan on stocking 4-6 Oscars (w/1 or 2 common plecos) or a ton of mbunas/haps/peacocks. Atm im leaning towards the oscars. As for substrate im planning on using some kind of sand, not sure yet which type but i heard pool filter sand is good/cheap. (Not sure where to get them though)
4-6 is probably going to be too much. Bioload shouldn't be a problem with adequate filtration and water changes, but I think you'll run into aggression issues with more than 2 (especially when the get large/pair). Pool filter sand is a great choice. Any place that sells pool supplies should have it.
So a few questions about the Oscars: What type of plecos should i include with them, I figured the common plecos grow to a fairly large size so this will be somewhat decent company with them. If there are better types what type would they be and why? How many Oscars should i be able to stock in the 125 Gal with a decent filtration.
Anything that is big enough to not fit in the oscars mouth will be fine for a pleco. Commons will work but may eventually get too large. I would go with a pair of oscars and several dithers, or perhaps you could get lucky and other large central/sa cichlids to get along with them. There will be a lot of trial and error.
Now my plan is to create a sump filtration for this tank as its main filtration and water circulation. As for the pump that i will be using, the nearest home depot I have in my area is selling Maxflo pumps, that pumps at max 4500 GPH, at 10' head it does about 3200GPH ($226 w/tax). (Is this type of pump somewhat decent/recommended for use of sumps for fish tanks) Now the 10' head is my estimate of how much the length of the water needs to travel to go into the tank. (6' to go up and 4' is the length i plan on using for the spray bar.) I know i have a huge turnover for this tank but i figured huge fish with big poop, a monster filtration is needed, plus i plan on slightly overstocking to prevent aggression between small number of fishes.
Wet/dry filters are awesome. However, I would not flow that much on that tank. It's not necessary. If you flow 3x per hour the water will be clean and clear. If you get some floating particles from the messy oscars you can add a powerhead with a sponge or a HOB for added mechanical filtration. I would look into a pump online which will use less power and cost less initially. I'm a huge fan of reeflo sequence pumps. Very efficient and they have a good warranty as well.
As for the overflow box im really not sure how big it should be at least close to 1500-1600 GPH. In terms of the sizes of the slit, LxWxH of the box itself, how far off it should be from the top and sides to make cleaning the sides easier. Any suggestions for this would be great. Now once the size of the overflow box is determined, now i need to know how far off the sides and from the top my tank should be drilled, starting from the bottom of the black trimming?
If you're getting a HOB overflow box then you won't have to worry about it. Always make sure that it can flow more than the pump.
If you're drilling the tank (in the back) you still don't need the overflow box. You can then use a bulkhead fitting and some PVC.
Now as for the spray bar, should it be submerged or on top of the water. I figured depending on how strong the flow would be if over the water it may be shooting at a strong pressure with holes. But if it was a long slit line would it create a waterfall effect or would it still shoot out at 3200 GPH at a strong rate. Also i have thought about adding holes on the sides and a few smaller ones as well aiming at the bottom of the tank, but would it disturb the sand at the back of the tank a lot like pushing it forward? Also what ways can I set this up so that if there was a power failure the water wont come gushing down my sump if i did end up submerging it underwater?
I would install it right at the water surface so you can adjust it to either direct flow up or down. You can go under water with out a problem. You don't need to worry about surface agitation because of the wet/dry. Also, as long as you drill a small hole in the PVC right below the water line, you won't have to worry about it siphoning back into the sump.
Also I plan on using ball valves in both the intake and my return line, so that i can perfectly match the flow and return. Also in terms of the maintenance, is their a proper way to turn off the intakes/return line first?
There isn't a need for a ball valve on the overflow. You're not matching flow from the overflow to the pump. Think of it literally as an overflow. It can only take out as much water and the pump returns to the tank. In other words, whatever water is displaced by the water coming back into the tank will overflow into the sump. You run into an issue when the pump delivers more water than the overflow can take out. In that case you can use the ball valve after the pump to reduce the flow (don't worry, it wont hurt the pump. It'll actually use less power and last longer with it choked down.
As for my sump/WD i plan on using those plastic drawers to hold my medias maybe 3-4 drawers sitting on a huge plastic containers, now is there any long term problems with using these, maybe leaking out chemicals overtime into your tank? Also i have heard that most plastic containers will bow once water is put in, what are the best ways to support or prevent these, because i plan on using as much as i can of the sump container to maximize water volume within my tank.
That plan is fine. Just build a frame around the container to keep it from bowing.
In terms of heating would a 200 Watt and a 300 Watt heater do the trick? I will also be using (3x-4x) 34 Watt florescent bulbs. Around 6-8" above the water.
Unless the room gets really cold, that'll be fine.
