Return Line - loc line or "waterfall"

Willhersh34 · Jan 25, 2022

I'm getting ready to replumb my return line. I have plumbing worked out, valves, pump, unions, etc. My question is on entering the DT. I don't have a drilled tank so right now I'm just using PVC elbows and cascading into the tank using an elbow in tank to direct current. I'm looking for feedback on whether I should just let it "waterfall" into the tank or use loc line and/or a return jet.

Flow isn't an issue so I'm just looking for some input and feedback as to what others are doing. Surface action and gas exchange are also not an issue as I have my flow pumps in-tank handling those duties for the most part. Tank is a 40 breeder and I'm pushing ~300 GPH through the overflow and return pump. Head pressure isn't a factor here as I have my DC pump running at roughly 45% capacity and it's driving water through the overflow as expected. I just want some ideas before I start building the new plumbing out. Have a plan, work the plan kind of stuff.

Reefer5640 · Jan 25, 2022

In my opinion, if flow isn’t an issue in the tank and you just need to get the water back up into the tank. And if the elbow doesn’t blast the corals or disrupt the sand or splash everywhere then you could just go with an elbow. You’ll have an open hole for critters to crawl into though. The lock line is just more convenient to direct flow, less messy, and prevents critters from crawling inside. I use them on all of my tanks. But I have gone without to get by for a bit at times too. Hope that helps.

Starganderfish · Jan 30, 2022

I had a waterful in my (tiny) Pico tank and it worked fairly well. Great surface agitation for air exchange and great for surface skimming. Doesn't do a whole lot for flow. It can also take a while to settle down and stop dumping microbubbles into the water, my tank was "cloudy" for several weeks, but it settled down eventually. Its a struggle to use floating food as they get pulled under the water quick. You also get a lot more salt spray and evaporation so an ATO is highly recommended. With a waterfall, there's no chance of a back siphon if the pump fails, which is handy if you're running it over the rim of the tank.
Personally I prefer the regular "return in the tank" idea though. Less spray and splash and it's basically an extra source of flow for "free" without requiring an additional wavemaker or pump. It's also a lot quieter - a waterfall is constantly splashing water, if the tank is in a room that's used a lot.