Marinand CornerFlo: Where's your overflow level at??

[Phyber]

I set this tank up this year after a hiatus from the hobby. Tank's been running fine, but the overflow box water height isnt where I remember it being.

I remember having the little plastic pipe sticking in the durso hole, and the level being about middle of the "U" fitting. Now, if I even run the pipe the overflow height surges constantly. I just leave the pipe off and it stays the same height.

Only difference I made hardware wise was replacing my Mag3 return pump with a Sicce 3.0, no restrictions on either. On the overflow drain outlet, I still run filter socks like before, but this time felt vs mesh. Same piping otherwise as before.

Any ideas? Anything to worry about? Tank will recover fine from power outages or return pump power offs.

 

[Dr. Bull]

If there is a small hole at the top of the overflow pipe try sticking a piece of ridgid airline tubing in it, about 2-3" should do. Don't push it down to the water, just put it in far enough to hold.

Secondly I have noticed with my perfecto/marineland durso overflows is that they have a point where you start trying to push too much flow through them and they start surging or flushing. (ie. fill the overflow box up with water, then flush it down fast) I have found that you need to tune the return flow to your tank down a bit until the flushing stops, then start opening up the flow slowly until you find the point where it starts flushing again. It should be easy enough to find the max flow point for the overflow by using this method in order to end the flushing cycle. The pump you upgraded to may be pushing more GPH than the overflow box can handle, so you may need to just dial it back a bit. If it is not a controllable pump then I suggest installing a GATE valve on your return line in order to fine tune the return flow.

 

[Phyber]

If there is a small hole at the top of the overflow pipe try sticking a piece of ridgid airline tubing in it, about 2-3" should do. Don't push it down to the water, just put it in far enough to hold.

Secondly I have noticed with my perfecto/marineland durso overflows is that they have a point where you start trying to push too much flow through them and they start surging or flushing. (ie. fill the overflow box up with water, then flush it down fast) I have found that you need to tune the return flow to your tank down a bit until the flushing stops, then start opening up the flow slowly until you find the point where it starts flushing again. It should be easy enough to find the max flow point for the overflow by using this method in order to end the flushing cycle. The pump you upgraded to may be pushing more GPH than the overflow box can handle, so you may need to just dial it back a bit. If it is not a controllable pump then I suggest installing a GATE valve on your return line in order to fine tune the return flow.

Indeed, there's a small hole and I have the plastic "straw" that the tank came with. When I put the straw down in any sort of depth, the water level will fall but indeed will start surging.

I've tried adjusting the return pump down with my valve and there's a fine line between doing nothing for the surging, and the return pump being pointless and not returning anything. Can't seem to find that line.

 

[Dr. Bull]

What are you using on the overflow to go from the bulkhead on the bottom of the tank to the sump? Flexible tubing, pool hose, or >=1" PVC? In order from worst to best when dealing with flushing syndrome.

 

[Phyber]

What are you using on the overflow to go from the bulkhead on the bottom of the tank to the sump? Flexible tubing, pool hose, or >=1" PVC? In order from worst to best when dealing with flushing syndrome.

I have 1.25" pvc from the bulkhead to sump. No 90* elbows, but a few 45* to get the job done.

 

[AdamW0611]

I have that setup, and my level is around where the hole is in U pipe. I actually wish I could get it a bit higher to alleviate some of the trickling water sound.

 

[Dr. Bull]

I have 1.25" pvc from the bulkhead to sump. No 90* elbows, but a few 45* to get the job done.

Try reducing the flow way down to where you know it will stop flushing. Then shut the pump off completely to let the lines drain for a min or two. Then fire it back up and "slowly" turn up the return flow let the tank settle for five to ten mins to see if if starts flushing or not, then if not turn the dial another tiny bit. etc. etc.

 

[ca1ore]

Flushing almost always means too much flow for the durso to properly handle. New pump must be pushing more water than the old one.

 

[Dr. Bull]

Those old marineland/perfecto "reef ready" tanks are really only good for pushing about 300-400 GPH through the durso without issues. You needed a double corner overflow setup to get upwards of around 700 GPH through the 2 durso corner overflows.

I run an older marineland 75 gallon reef ready and a 150 gallon reef ready with single corner overflows, and both are dialed way back in order to prevent the flushing. I prefer a slower flow through my sumps anyway in order to match the skimmer's pump, as well as to keep the return flow low enough for my in line UV sterilizers to work properly. Just have to realize the limits of the setup and work with what you got.

As for the change when swaping pumps, they could be rated at very similar GPHs but one could be better at dealing with head loss over another, which would allow one pump to push more water back to the tank in the same plumbing scenario.

 

[Phyber]

Those old marineland/perfecto "reef ready" tanks are really only good for pushing about 300-400 GPH through the durso without issues. You needed a double corner overflow setup to get upwards of around 700 GPH through the 2 durso corner overflows.

I run an older marineland 75 gallon reef ready and a 150 gallon reef ready with single corner overflows, and both are dialed way back in order to prevent the flushing. I prefer a slower flow through my sumps anyway in order to match the skimmer's pump, as well as to keep the return flow low enough for my in line UV sterilizers to work properly. Just have to realize the limits of the setup and work with what you got.

As for the change when swaping pumps, they could be rated at very similar GPHs but one could be better at dealing with head loss over another, which would allow one pump to push more water back to the tank in the same plumbing scenario.

Flushing almost always means too much flow for the durso to properly handle. New pump must be pushing more water than the old one.

I'll give it a go dialing my newer return back down...I remember matching my previous one to my skimmer pump (giving the skimmer more time to skim the same water) but was trying to get more flow going back in the tank wherever I could.

I just wondered if it was time to get a flexible brush and scrub...the overflow output pipe looks like a fire hydrant into my sock so I wouldn't imagine too much getting built up in there.

 

[Dr. Bull]

I'll give it a go dialing my newer return back down...I remember matching my previous one to my skimmer pump (giving the skimmer more time to skim the same water) but was trying to get more flow going back in the tank wherever I could.

I just wondered if it was time to get a flexible brush and scrub...the overflow output pipe looks like a fire hydrant into my sock so I wouldn't imagine too much getting built up in there.

Your better off dialing in your overflow to a comfortable flow rate for the system, and achieving more flow in the tank with powerheads.

 

[Phyber]

Your better off dialing in your overflow to a comfortable flow rate for the system, and achieving more flow in the tank with powerheads.

I'm guessing when I go dialing I need to keep the straw in the hole? Any pro or con with leaving it off?

 

[Dr. Bull]

I'm guessing when I go dialing I need to keep the straw in the hole? Any pro or con with leaving it off?

The straw just lets air into the overflow standpipe to help with the siphon, as long as the hole is above the surface of the water you should be good without it. I always leave a small piece of ridgid tubing in there just in case, since the hole on its own can easily get clogged by something. Like I said before though do not shove the straw way down into the tube, just insert it enough into the hole so it holds and lets the air in. It should not be inserted into the "inside" of the PVC pipe where it will come in contact with the water.