Problem with my drilled tank overflow...

[electricd7]

Hello,

I have had my 46gal tank up for a little over a year. In the last week or so my sump began to run dry. When I opened the hood, I found that the water level in the tank had risen the 3 gal extra that the sump used to hold. I have a 1" hole with a 90degree elbow and a strainer installed in the corner opposite the return tube. It worked flawlessly for over a year. I started messing with it, and finally got it working full again (had to turn the pump down to compensate for the lack of overflow.) Anyway, I did a 5gal water change today. Turned off the valve to the overflow, unplugged the pump, and turned its valve off like I always do with water changes. When I opened it all back up, the system is having the same problem as before. The overflow can't keep up with the pump! Not sure what the issue could be. The pump is a MAG7, overflow is 1", sump is a custom 15gal with a pump resevoir of about 3-4 gallons. Thanks for any help in advance!

ED7

[cdbias2]

Your over flow is considered a weir. If it gets clogged it will raise the water level in the tank. this even happens on the AGA's when the grill gets filled with coraline algea,

[Lucky-rc]

I have also seen the ball valves break so that hen you think your turning it the sctusl vslve inside does not open fully (just something to check) But I'd say your over flow box lines need changed. Always good to replace them from time to time.
When you take the line of smell it and you'll understand why.

Lucky

[IPT]

Had a snail block mine. Luckly for me I have (2) 1" overflows and the backup made up for the rest. I wasn't sure why the difference in flowrates because it was tweaked perfectly for a long time. Crnked open my gate valve on the main drain and instanlty heard the "chink" of a snail shell hitting my sump bottom.

You need to pull your plumbing and look for either a large blockage, or just plain and simple build up of "sludge" which slowly narrows the diameter of a pipe.