Help Explain Sump/DT Level Relationship:

[Bevo5]

I’m a bit confused as to how the sump and DT water levels are related. I thought it was as simple as the DT would always stay the same level as my overflow, while the sump level would fall due to evaporation. I just set up my 200g with about 40g in the sump and I’m having a hard time keeping it all perfectly level.

 

I’m judging the DT water level with my emergency drain. I want to keep it at a very slight trickle so the water level is right up to the edge.

 

I got the sump right where i want it and marked it with a piece of tape. Came back later that night to top off and I poured water into the sump to get it to where I want it. This ended up somehow pushing my DT level a bit higher as the emergency started to get a good stream of water in.

 

Also - when I don’t top off for a while I notice the water level around the emergency drain is lower.

 

The entire time, however, my pump is completely submerged in the sump. I can’t wrap my head around how the DT could be any bit higher or lower when the pump is steadily pushing the same amount of water nonstop.

 

What am I missing here?

 

My plan is to put the ATO in the return part of the sump and just keep that level as it’s the lowest baffle. 

 

I always thought once I got the sump level stable the DT and overflow would stay level. As it is now I’m having to constantly adjust my gate valve to keep everything where I want it.

 

 

Thanks.

[Blue Z Reef]

Sump level is all that should be changing assuming pump speed is maintained. Sounds like you're running some form of a Herbie drain. Once started, Herbie drains take a few minutes to purge air and get up to full draining. In your case I would suspect something with the drain is slowly changing, is it possible there is a leak somewhere? Maybe air is getting in and slowing it down or making it take longer to get up to speed? I would investigate the drain first and go from there.

 

Also, auto top offs help keep the level in your sump constant to avoid any fluctuations caused by topoff that could somehow be affecting the pump.

[Blackice]

It's really just as simple as the return pump fluctuate it's flow slightly throughout the day based on a lot of things (how dirty it the screen is, how much power it's get ect). I find I have mine from time to Time that is normal as long as the main drain is not cavitating it really don't mater where the water line is on the emergency line.

[danlu_gt]

This sound normal to me. When your sump have more water, the distance your return pump need to push water is slightly less, thus less head pressure, thus slightly more flow. When sump level drops, more distance, more head pressure, thus less flow.

 

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[Bevo5]

Interesting - thanks for the responses so far.

 

It's a brand new set up so I'm just figuring out how to dial it in. I don't hear any air getting in or see any leaks (knock on wood!). The main drain is 100% full siphon right now so I just can't figure out how more or less water is getting pumped in to make that change. It would make sense that the pump is shifting slightly as the water levels change etc. It doesn't matter to me where the water line is on the emergency, I just figured it would stay constant.  

 

The tank will have an ATO once I get it up and running. For now I'm just pouring in to the water line I marked in the sump. 

 

I just need to spend some time with it to figure out the best system.

[Bicyclebill]

What pump are you using, what diameter feed line, what diameter drain bulkhead? It's a fine balancing act to get the pump to deliver just enough water to keep from filling the display faster than it can drain. I would recommend turning your return pump back just a hair and see what that does.

[Bevo5]

It's not pumping more than the overflow can handle - i'm just trying to get it to stay perfectly balanced which seems hard.

 

The pump is a Jabeo 12000 at level 3 of 5. The main return is 1.5in straight down to sump. The emergency is also 1.5in.

 

I've tested the pump at 100%. I've tested the sump with all power off. Everything seems to be fine there. Just a matter of fine tuning hopefully.

[Higher Thinking]

This sound normal to me. When your sump have more water, the distance your return pump need to push water is slightly less, thus less head pressure, thus slightly more flow. When sump level drops, more distance, more head pressure, thus less flow.

 

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This exactly! I have just learned this recently setting up my 180 gallon. When the sump has more water it will actually have a higher level in the overflow compared to when it has a little bit less water. Just like mentioned, if there is more water in the sump that slight increase in water creates less head pressure which means you're technically pumping a little bit more water than you were when there was less water in the sump. If that makes sense.

 

 

Side note: I'm also using the DCT 12000.

Edited November 21, 2015 by Higher Thinking