New (to me) 125

[THE V]

Sumps are great for filtration and the health of the tank. There's just two side effects with a sump.

If you use a sump you'll limit yourself from using CO2 in the future. The CO2 will offgas out of the water when it goes through the sump. This means that most of the CO2 that you pump into the water will not be available for the plants. If you sure that you will not do C02 in the future then go for it.

The second downside is the sound. If you like the sound of running water then it's for you. It annoys me so I stick with a canisters.

If I were you I'd start with looking at what plants and stocking you want. Then you can put together the rest of the tank around what you choose. It's a lot of fun to figure out the substrate, hardscape, lighting, etc... to fit your plants and stocking.

[stephcps]

The sound and potential to drain your entire tank if there is a problem are reasons I don't use a sump. II know there are check valves and things to help keep it from happening....but you read a good deal of horror stories. No thanks. The noise is also pretty impressive. Again...there are stand pipes etc that can make it better...but again....

[dudley]

The Eheim 2217 would probably be a good choice for a canister with the fish you posted above but wouldn't be sufficient as the sole filtration. You can always add a power filter to supplement the filtration. On most sites they are called HOB or Hang On Back filters.

I have no trouble growing moss, Java Fern, Anubias nana, and some swords in my 75G or 125G tanks without CO2 supplementation. I do dose Flourish Excel once a week after my water changes so that does help a bit.

One issue with floating plants is the potential to clog up the intakes of your filter. You can always add a sponge prefilter to the intake screen that minimizes clogging but it does require frequent cleaning or observation.

I use Eheim Ebo Jager heaters in my tanks without canister filters but you may want to consider the Hydor ETH 200W heater which is an external heater used with canister filters or pumps. I have 3 (various wattages) on my large tanks and highly recommend their use. Just make sure you purchase the appropriate size based on the hose diameter of the filter you decide to buy.