Overflow Tuning Issues

[NotoriousENG]

Hi Everyone,

During leak testing of my new 20-gallon long build, I noticed an issue with tuning the overflow. The overflow is an Eshopps Eclipse S plumbed in standard Herbie style with a gate valve from BRS on the main drain. The return is loc line over the back coupled with a DCP 2500.

I am having two issues. The first is that at pump powers much above 40% the overflow level is not constant. I'll tune it so the emergency drain is just barely trickling and it will be fine for a while. Suddenly, the water in the overflow will drop quickly till the main drain starts sucking air. If I let it keep go like this, the water level will usually slowly creep back up. The tank level seems to be staying constant, just the level in the box.

Second issue. I am getting a lot of noise from water falling into the weir box. I've tried to counter this by running the water level higher and the emergency drain a bit wet. However, then the emergency drain gets noisy even with just the slightest trickle. Any help would be appreciated.

 

[T-J]

If your drain line is making noise, that means it is not able to produce a siphon. I'm guessing that your pump isn't pumping enough water. That overflow is rated at 600gph, your pump is max rated at 660gph, that's with zero head pressure, so even at max, if you're pumping water up into your tank, you're well under 600gph.

 

[NotoriousENG]

If your drain line is making noise, that means it is not able to produce a siphon. I'm guessing that your pump isn't pumping enough water. That overflow is rated at 600gph, your pump is max rated at 660gph, that's with zero head pressure, so even at max, if you're pumping water up into your tank, you're well under 600gph.

The main drain is silent and definitely running at full siphon thanks to the gate valve I've used to choke it. It's just that the overflow box has a strange cycle thing going with the water level at pump levels above 40%. The water level runs as it should with a slight trickle down the emergency drain for 10 minutes to half an hour. Suddenly in about 30 seconds of time, it drops to 50% or lower in the overflow box. A few minutes later it returns to the proper level.

The emergency drain is loud however, this is unrestricted and open so the lack of siphon makes it loud even with a little trickle. The other place noise is coming from is water falling into the weir box on the inside of the tank. Again this only noisy at higher pump levels (above 40%). At low power, everything is quiet and working as it should.

 

[T-J]

The main drain is silent and definitely running at full siphon thanks to the gate valve I've used to choke it. It's just that the overflow box has a strange cycle thing going with the water level at pump levels above 40%. The water level runs as it should with a slight trickle down the emergency drain for 10 minutes to half an hour. Suddenly in about 30 seconds of time, it drops to 50% or lower in the overflow box. A few minutes later it returns to the proper level.

The emergency drain is loud however, this is unrestricted and open so the lack of siphon makes it loud even with a little trickle. The other place noise is coming from is water falling into the weir box on the inside of the tank. Again this only noisy at higher pump levels (above 40%). At low power, everything is quiet and working as it should.

What size plumbing is your main drain? Is it PVC or flex?

 

[NotoriousENG]

Main and emergency drain are both all 1" sch 40 PVC. The main drain has only 45 elbows (4 of them). Emergency drain uses 90 degree elbows due to space constraints (2 of them). The return line is a mix of 3/4" PVC and vinyl hose. The return also has a CO2 reactor T'ed off of it (this for a freshwater planted tank).

Note that I switched the return and emergency lines from their locations in the below picture. The plumbing is unchanged, just switched the bulkheads they are attached to. I am using the red emergency standpipe that came with the eclipse overflow inside the overflow box (not shown in the second picture).

 

[NotoriousENG]

Shameless bump since this issue is really frustrating me.

 

[38bill]

Don't know if it helps but I had an issue with my 2 pipe ext overflow box. The main drain line would create a vortex that would suddenly suck air into the drain and upset the balance between the 2 drains. I made up a short pipe (with a U on top) that fit into the main drain bulkhead. I also made a taller emergency drain pipe. These changes raised the water level in the overflow while it kept the main drain inlet low and problem solved.

PS: The sump looks a little too full in the photo. Make sure the water level in your sump is low enough so it can't overflow when the pump shuts off.

 

[NotoriousENG]

Don't know if it helps but I had an issue with my 2 pipe ext overflow box. The main drain line would create a vortex that would suddenly suck air into the drain and upset the balance between the 2 drains. I made up a short pipe (with a U on top) that fit into the main drain bulkhead. I also made a taller emergency drain pipe. These changes raised the water level in the overflow while it kept the main drain inlet low and problem solved.

PS: The sump looks a little too full in the photo. Make sure the water level in your sump is low enough so it can't overflow when the pump shuts off.

With the standoff that was included with the overflow, I haven't noticed any vortex on the main drain as long as the overflow water level is high enough. However, the vortex is an issue on the emergency drain that I noticed during clog testing (gate valve fully closed). The overflow box seems to have been designed to short so that the emergency drain is unable to pull full siphon due to sucking air from the surfaces in a vortex. As a result, I don't think I will ever be able to run the pump much above 70% as the overflow box would flood if the main drain ever clogged.

Thanks for your concern on the water level, no one ever wants a flood. However, as pictured the sump is at a water level where if the pump is shut off the water that drains back in raises the level about a 1/4" below the top of the sump. My siphon break on the return is right at the surface and I have the overflow mounted flush to rim lip so the main tanks level only drops about a 1/2" when the pump shuts off. The sump also doesn't have any baffles so the water level in the sump has a wider allowable operating range as long as the sump doesn't flood during a power outage and the pump is fully submerged.

 

[Reef Tripp]

The secondary line, the one that does not have a regulation key, has to be a little higher than the primary line, add a piece of pvc on that bulkhead

 

[KStatefan]

As @Reef - Tripp said it is going to be impossible to tune that when the primary and emergency are the same height. You can not do it exactly like this picture due to how low the outside box it.

 

[NotoriousENG]

The secondary line, the one that does not have a regulation key, has to be a little higher than the primary line, add a piece of pvc on that bulkhead

I do have one there, it just wasn't in the first batch of pictures. Sorry about that.

The green sponge on the left is a prefilter I am testing (to avoid sucking up shrimp). I don't think that is the issue since the variable water level occurs with or without it installed.

 

[NotoriousENG]

Pre-filter pulled out to show the inner workings. The riser is the one included with the overflow and has been in use for the full time during leak testing. The original picture without it was prior to leak testing.

 

[Reef Tripp]

The stopcock has to be adjusted so that only a thread of water flows through the red tube, as little as possible until silence, as I see the image, open the tap a little and wait a little before adjusting again

 

[takitaj]

Long but it's all important:

Look at @KStatefan 's picture. Does your's look like that? The emergency drain has to be higher than the main so the level can fluctuate a little in the box but will keep full siphon on the main (no air). The emergency should be at least a couple inches higher than the main but below the normal water level in the tank.

Now the sump; You want at least one baffle to separate the return pump area from the rest. This will set the height of the water level in the sump. (piece of acrylic/glass or after market baffle system) The baffle should be 8-9" tall so if you decide to add a skimmer later the level will be correct. The aftermarket baffles are usually adjustable and even better than just a sheet of acrylic. They're siliconed in place. The baffle should give a 5-7" wide area for the return pump. (depends on how physically big return pump is) Now when water evaporates the level in the return pump section will go down while all the other levels will stay the same. The return area is where you will monitor the level for an Auto Top Off (HIGHLY recommended) or where you will visually monitor evaporation and add top-off water. (fresh water only, RoDi) The water level in the rest of the sump should be just high enough to roll over the baffle.

Now open the main valve all the way then turn your pump up to 100% or at least 80% if the pump is too loud at 100%. Wait and watch for a 1/2 hour or so then start closing the main valve until the water level in the overflow box stays above the main outlet and just below the emergency. The bubbles coming out of the drain should stop. Watch and wait, adjust as needed and repeat until it's right.

At this point you should be real close to perfect and may need some very slight tweaking later to get it just right, maybe not. It won't work correctly unless you set it up correctly so you can't skip steps or it won't work as expected.

Also as noted previously your sump has to have the capacity to hold any additional water that flows back when the return pump shuts off; ie: power outage, pump failure, etc.. Reducing the level to the 8-9" of the baffle will help here.

 

[NotoriousENG]

@takitaj Thank you for the post, lots of very good information there!

I just want to clarify a few things since I think I created some confusion with some of the pictures I originally posted. I apologize for that and it is fully on me.

I do have a riser on the emergency drain in the overflow box. It is the red one included with the eclipse overflow. Through leak testing, I have consistently run the overflow with a slight trickle down the emergency drain. More recently, I have been running more than a slight trickle as an experiment to see if it had any effect on the main issue.

The main issue I am worried about is that I can set the gate valve so the water level is perfect in the overflow box. Just a slight trickle down the emergency drain. Then everything will run fine for a while. Eventually, the issue appears in that the overflow level is suddenly sucked down over about 30 seconds span so that the main drain is sucking air. About five minutes later the water level has risen and everything is running as it should - full siphon on the main drain, slight trickle on the emergency. About 30 minutes later the cycle repeats - water level drops quickly then rises back and runs as it should. This only seems to occur at pump power levels above 40% and is intermittent only occurring randomly. I work from home so I have been watching it run for the past week and have been trying to tweak the valve to avoid it. Some days I never see it, other days I see it a bunch even if nothing changed from the previous day. Today for example I have been trying to induce it to grab a video to post and it hasn't happened yet. Thursday, on the other hand, it was happening extremely frequently and was driving me insane. I will give the method of running the main drain wide open for a half-hour before slowly closing a try to see if that helps.

The secondary issue I am having is noise. The main source of the noise is the water falling into the weir box. To try to reduce this I have tried running the overflow water level higher which helps some. However, if it gets too high the emergency drain takes too much flow and gets loud. I also don't think using a longer riser on the emergency drain is a good idea since the eclipse box seems to be designed too short. If I close the main drain all the way (to simulate a clogged drain) the emergency is not able to achieve full siphon due to sucking air for the surface and the water level rises dangerously high as shown in the picture below.

In regards to the sump level baffles. I apologize for not clarifying that this tank is going to be a "high-tech" freshwater planted tank. As such I don't need a constant water level for a skimmer. I was actually originally planning to use a more traditional sump design with baffles. However, since I am running CO2 injection on this tank (the filter housing attached to the return is the reactor to dissolve the CO2 gas), I decided to go with a baffle-free design to limit splashing in the sump in order to reduce CO2 off-gassing (CO2 can get costly...). I don't see any issue with not having baffles in this specific circumstance but I may be missing something?

The sump water level is something I am very conscious of since I live in an apartment. As a result, I have carefully watched and planned to ensure the sump will not overflow. The first picture below shows the sump at the maximum allowable level during pump operation. The second picture shows the sump with the pump stopped after the overflow and return lines have all drained. The main display tank water level drops very little when the pump is turned off due to having the overflow flush with the top lip and having the return siphon break right at the water level. During the real operation, I will likely run the water level a bit lower as an additional safety net. I do plan to get an ATO as soon as my budget allows. Until then I will be manually topping up with distilled water if evaporation is significant enough to require it (large water changes will be performed weekly so I might not need to).

Once again I appreciate all of the replies and advice and apologize for any and all confusion.

 

[KStatefan]

There is really no way to eliminate that noise when the outside box is that much lower then the water level in the tank

 

[NotoriousENG]

There is really no way to eliminate that noise when the outside box is that much lower then the water level in the tank

I was worried about that. Just a design flaw of the eclipse overflow I guess since there's no way to mount the overflow box higher.

 

[Jivatma]

I was worried about that. Just a design flaw of the eclipse overflow I guess since there's no way to mount the overflow box higher.

When i did my research on overflow boxes, this was a common complaint amongst eshopps and braced tanks. Only reason i went elsewhere. You might be able to reduce some of the splashing with some filter media or something, but i think youre stuck unless you change overflow boxes.

 

[NotoriousENG]

When i did my research on overflow boxes, this was a common complaint amongst eshopps and braced tanks. Only reason i went elsewhere. You might be able to reduce some of the splashing with some filter media or something, but i think youre stuck unless you change overflow boxes.

Unfortunately that it's an issue since it seems to be a great product otherwise. I have been playing around with placing something in the weir box to help quiet it down so we will see if I can find something that works.

In regards to the issue at hand, it was suggested on another forum that my main drian extended too deep into the sump. I cut a few inches off so I will see if that and purging the line before adjusting the valve fixes the issue after the paint is fully dry.

One thing I started thinking and worrying about this weekend was flooding the main tank if the weir teeth clog. With two drains and the sponge prefilter on the main, I'm comfortable with the level of risk of clogging a drian. However, clogging the weir teeth seems like a much more likely issue. Since the water level is quite high in order to have it above the bottom of the rim even installing a baffle near the pump likely wouldn't be enough to prevent flooding the display tank. One solution I am thinking about is to shave down the side edges of the weir box just enough so that if the teeth clog water can pour over the sides of the box before flooding the tank. Does anyone see any issues with this?

 

[DaddyFish]

Unfortunately that it's an issue since it seems to be a great product otherwise. I have been playing around with placing something in the weir box to help quiet it down so we will see if I can find something that works.

In regards to the issue at hand, it was suggested on another forum that my main drian extended too deep into the sump. I cut a few inches off so I will see if that and purging the line before adjusting the valve fixes the issue after the paint is fully dry.

One thing I started thinking and worrying about this weekend was flooding the main tank if the weir teeth clog. With two drains and the sponge prefilter on the main, I'm comfortable with the level of risk of clogging a drian. However, clogging the weir teeth seems like a much more likely issue. Since the water level is quite high in order to have it above the bottom of the rim even installing a baffle near the pump likely wouldn't be enough to prevent flooding the display tank. One solution I am thinking about is to shave down the side edges of the weir box just enough so that if the teeth clog water can pour over the sides of the box before flooding the tank. Does anyone see any issues with this?

Or run a water level sensor inside the DT and shut down the return pump???

Ooops!!! Bad idea!!!
You'll need a different sensor as this one is rated for 1/4" thick glass maximum. I'll look again.