Converting CornerFlo (durso) to Herbie?

KGNickl · May 25, 2020

So I have a new Marineland 75 gallon with a cornerFlo (durso). Its surging and noisy and I've figured out its because I need to slow my pump down. To do this I would need a valve since the pump is already at the lowest setting.

Not reading much good stuff about the durso so I was thinking I can really easily convert what I have with a few extra parts to be a herbie. Since my big cost will be the valve I figure I'm probably better just buying using it to convert to a herbie on the drain vs. using it on my return to slow down my pump on the durso setup. I think I have PVC and other stuff laying around. Only cost will be the valve.

Does the below sound right? Am I missing anything or doing anything wrong?

Step 1: The return is a 1" bulkhead and 1" PVC. This will become my emergency drain. In the overflow I just need to cut the PVC and have it be where i want the top water level to be in the overflow. If its a little to short I might have to extend the pipe a little but I'm thinking it might be good w/ just cutting. Under the bulkhead I will cut the pipe and reroute it into the beginning of the sump.

Step 2: The drain in the overflow is a 1" bulkhead that increases to 1.5" PVC. I just need to cut the top of the 1.5" pipe so its about 6" below the new emergency line. Add a strainer. Then under the bulkhead I need to cut the current pipe and add a gate valve for fine tuning. Is there any issue using the 1" to 1.5" pipe? I'd rather not have to buy a new bulkhead and run a 1" pipe up to the top.

Step 3: Take the old return line that was cut and redo it so it goes up the back of the tank, into the overflow, and back to where it used.

Ron Reefman · May 26, 2020

I think you are OK here. The 1" to 1.5" pvc isn't an issue.

I'd like further explanation to the new return line. Is it going into the overflow behind the weir and connecting to the old nozzles that release the return water into the main tank?

It's just an unclear point. It kind of sounds like you are releasing the return water into the overflow, behind the weir which would not work.

F i s h y · May 26, 2020

I just did this on a 75. You can check it out on my build thread (click on my badge above). The one thing that you may want to change is IMO the larger should be your emergency drain. That way if the smaller is clogged you are 100 percent sure the emergency can handle the full flow of the pump. May change the gph going to the sump, but if its strictly filtration and not your main movement then it should be fine. Also, i put the returns on the opposite side. Since you are going over the back be creative you can do anything you want.

Ron Reefman · May 26, 2020

Fishy65 said:
I just did this on a 75. You can check it out on my build thread (click on my badge above). The one thing that you may want to change is IMO the larger should be your emergency drain. That way if the smaller is clogged you are 100 percent sure the emergency can handle the full flow of the pump. May change the gph going to the sump, but if its strictly filtration and not your main movement then it should be fine. Also, i put the returns on the opposite side. Since you are going over the back be creative you can do anything you want.