Originally Posted by Rohland
I personally would go with a Eheim canister filter and many members rave about how good it is. It would be a cheaper and better alternative than building a sump, especially for a fresh water tank. A sump is good for a salt water aquarium because it hides the skimmer, heater, ect. But in a feshwater tank its easy enough to hide your heater and filter intake and outtake tubes with some rockwork or plants. For 125 gal aquarium you are looking into I think around a 30 gal aquarium. You would need an overflow box, a good quality one as well as an excellent quality pump. There is a way to stop an overflow, its something about drilling a hole into the pipe so once too much water gets out the syphon will stop.
I think you are looking into a more expensive option, actually really expensive option that won't provide any benefit besides some hidden pieces of equipment, and leave you with a lot of cash missing from your pocket, and maybe even a broken or cracked tank if you need to drill it.
You have to be careful when drilling since it might be tempered and then you have no tank left. Also I disagree about the cheaper, Eheims are awesome filters, however they are also costly and come with no media, you would have to buy media extra. A canister will be at the very least 100.00 likely more then that, you can buy a pump capable of 3 - 6x turn over for 100.00 or 150.00 and plastic tubs make good sumps and they are cheap.
Hiding a heater behind a rock if you have monster fish is begging to have the heating case cracked which is extremely dangerous. Also be ware of overflow boxes, if you get one you need to check on it often, if air builds up the overflow stops and you flood the tank.
I personally agree in this case that a canister is better, only for the fact that they use less electricity, and can be hidden, they also make inline heaters you can plump to the canister. Sumps are great for large tanks, or multi tank filtration, and even over stocking. If you can aford to get a canister for your tank and have no plans of having multiple I say go canister.
Originally Posted by willieturnip
The only point in sumps is to hide the huge gear associated with marine and to increase your water volume to make it easier to keep parameters on the straight and narrow. Usually people get the biggest sump they can accommodate, because the bigger it is the more water there is.
Sumps are all but pointless with freshwater.
Why do you feel they are pointless? They server the same use in FW, give you more volume for more stability, and also a place to hide/protect your heaters.
I forgot to say that a 10gallon sump might be to small to hold the pump and the filter media, with a sump you have to have room for the media and the pump, plus have enough water that it can run without sucking in air. I had a 40 gallon tank on a 10 gallon sump and had to add water almost every day, to keep the water level in the sump at a safe level for the pump.