OK, so I found a leak and wanted to turn off the pumps in the hope of fixing it. I did and then a minute later....FLOOOD!

I turned the pumps back on but...my return pump wouldn't fire up. I panicked and worried my whole tank was going to spill out on the floor. I called KPotter2 and he talked me down as the water stopped flowing out of the tank. Thankfully.

I thought that maybe after putting in rock I'd gotten in too much water volume, but that couldn't have been it. I didn't put in that much rock. I'd tested the backflow before I started the tank and all was fine. What the heck?

I siphoned out the water to the previous pump off fill line and finally got my pump started again and when the water returned to the tank, I didn't even have enough water in the sump to run my skimmer. I dumped back in what I took out and all was fine. 

But what caused the overflow?

Then it hit me: Over the weekend I also extended my returns so they went into the water. I had one of them way down in the water to try and direct flow toward on place. It was extended just to the level where the water had drained when the pumps turned of.

Answer to the mystery: Backsiphon...

 

Right?

You got it. Best thing to do is drill a small siphon break hole in the return tube in the overflow box right below the water line. Just keep the hole cleaned out so it functions properly when the pump goes out.

Now the next thing is why your return pump didn't get started again. What pump are you running?

Are you using a quietone pump? They are notorious for not restarting after a power outage or unplugging them. I would highly recommend using a different pump for a return. Tanks Looking good BTY:-)

 I've got a maxijet 5500 utility pump. I got it back up once, had to power down again, wouldn't start again, I dealt with the water, tried it again and away it went. I'm gonna try and deal with the leak tomorrow or the next day and will try it again. This is the first time in my limiter use of the pump that its been a problem.

BTW, where exactly should I put the siphon break? That'll theoretically spray water when the pump's actually returning flow, right? As long as I keep the returns reasonably high in the taknk, shouldn't be a huge problem, right?

 

Yes there will be water coming out of them. You want them right below the normal running line of the water, and preferable aimed where the little jet of water won't splash into anything. Yes, another option is to keep the returns higher in the water, but then you can't always get the flow how you want it with them near the surface.

maxijet's are generally good pumps although I have never used their utility pumps only the powerheads.

Nice job Jason. I am glad I could help you stop and think. I have had a lot help me when doing this. We all do it from time to time and don't hesitate to call me again. See panic is got to be out of the vocabulary of a reefer when you have a problem, because you tend to forget about the last thing you did. its almost always what the cause of the problem is. Remember when I told you as long as your water goes below your overflow you should be fine, well that is why I ask you to look at that area. Its really a simple area, because as long as the water has no way to get to the sump it should not get to it. I am glad you remembered your return was lower and suggest you add a Y connecter. That way if you want to keep one below water and one above you will have a automatic anti-siphon. With out drilling a new whole in return line. This is what I was going to do, but never did. So I just put the line just level with overflow grid.

Happy Reefing.

you could also install a check valve on your pump then u dont have to worry about it backflowing