Fiji Cube Overflow Water Level

JCM · Mar 23, 2021

I recently installed an 800 GPH Fiji cube overflow. I used the provided template to set the water height. I set it so the water level was about 1.25" below the top of my rimless tank. Unfortunately when I filled the tank to leak test everything, the water level was about 0.5" below the top. This obviously won't work. Any ideas on how I can lower the water level? Cut the slots in the internal box deeper?

JumboShrimp · Mar 23, 2021

I’m trying to get a visual in my mind of your problem. Are you saying that when fully installed, the vertical slits in the weir box are only a half inch submerged under the water level in your tank?... and by that you fear there won’t be enough flow?

JCM · Mar 23, 2021

JumboShrimp said:
I’m trying to get a visual in my mind of your problem. Are you saying that when fully installed, the vertical slits in the weir box are only a half inch submerged under the water level in your tank?... and by that you fear there won’t be enough flow?

My problem is that when the tank is full and running, the water level is about .5" from the top of the rimless tank. That is too high in my opinion. I need a way to lower the water level in the tank.

Trever · Mar 23, 2021

Is this a flow issue- is the water level riding way up on the weir teeth because you're putting a lot of water thru it?

You're saying leak test, so maybe not...

The water level will typically be about 1/4" or so up the weir teeth. If there's still a lot teeth left above the water line, and the water line is .5" from the top, you apparently haven't done something correctly. Either you drilled too high or you have it mounted/assembled wrong, if that is possible (and for it to still work).

If you don't need a lot of surface agitation, I would imagine you could live with .5". Not ideal but it would work on my cube, for example.

JCM · Mar 23, 2021

Here it is while running. I'm leak testing outside and my carport is not level. If I average the two sides, the water level is .5" below the top of the glass.

JCM · Mar 23, 2021

Trever said:
Is this a flow issue- is the water level riding way up on the weir teeth because you're putting a lot of water thru it?

You're saying leak test, so maybe not...

Maybe? I'm testing with a mag7 pump. I would think an 800 GPH overflow would handle that pump fine.

JumboShrimp · Mar 23, 2021

Have you tried 1) lowering the water level in your tank to where you would like it to be, and then 2) cranking open your pvc pipe valves to see how much water (flow) you can still actually generate ‘wide open’? (Maybe even using a 1/4 of the emergency overflow pipe as well? I ask this because you might be surprised. I have the Fiji 2400 low pro and the thing really kicks even though part of my weir slats are above the water line.

Trever · Mar 23, 2021

I wouldn't fill it with unlevel water- that can stress the glass/crack. When I leak test I make sure to level (part of the reason I love stands with leveling feet, leveling has to happen several times during a build for me).

In the photo it looks high, so I doubt it is a flow issue. But it's hard to tell with the one side nearly going over the sides like that...

Those templates and drilling correctly... not trivial IMO. You may want to go back and look at the template and reason through it some more to see if you drilled and used the template as you intended.

Trever · Mar 23, 2021

Second what @JumboShrimp says, make sure your drains are draining properly, but this really should be about the level of the water on the weir teeth. If it's at a nominal level on the teeth, that is your water level, period.

In that second photo, the water level seems high on the weir teeth so you can push water at a lower rate to bring the water level down. Refraction is tricky here though, if I look from below on my overflow, the water looks higher than it is.

I think those Fuji's come with very long teeth though? I would think you can bring the water level down.

JumboShrimp · Mar 23, 2021

Wow, my eye wasn’t even looking at the leveling aspect, but like @Trever says— Is that tank really that unlevel? That needs to be addressed right away, even before whatever situation you have encountered with the overflow box.

JCM · Mar 23, 2021

Thanks for the input guys.

I had the gate valve on the main drain wide open during testing, I also lowered my emergency drain to verify it wasn't a drainage or water flow issue. It's not.

I also triple checked with the template before and after drilling, it showed the water line should be 1.25" below the top.

Yes, it's unlevel in the carport. It's perfectly level in the spot it will be though. I doubt that would cause cracking issues, the stand didn't rock before filling. No more likely to crack than having the tank filled to the brim.

I guess I'll use a dremel to lower the weir teeth. I'm far from impressed with this overflow.

JumboShrimp · Mar 23, 2021

I didn’t want to add to your problems and tell you the bigger problem: When you have it hooked up, cut off your pump. Check to see if the water ever stops trickling into the overflow box!!? In the end, I had to slobber my tubes with silicone, because when I complained to Fiji that water kept leaking into the tubes by bypassing the seals, and all they did basically was shrug and say, ‘yeah, sometimes the tubes don’t fit tight inside the bulkhead.’ To me it is a design flaw that can lead to a sump overflowing, if the tank is big enough.

JCM · Mar 23, 2021

Trever said:
Is this a flow issue- is the water level riding way up on the weir teeth because you're putting a lot of water thru it?

You're saying leak test, so maybe not...

The water level will typically be about 1/4" or so up the weir teeth. If there's still a lot teeth left above the water line, and the water line is .5" from the top, you apparently haven't done something correctly. Either you drilled too high or you have it mounted/assembled wrong, if that is possible (and for it to still work).

If you don't need a lot of surface agitation, I would imagine you could live with .5". Not ideal but it would work on my cube, for example.

I just noticed your edit. The water was definitely higher than .25" up the teeth. I'll try a smaller pump and see if that helps.

Trever · Mar 23, 2021

The stand didn't rock? Umm.... ok. That's a low bar?

You have what looks like a lot of water pushing against the sides very unevenly. Keep your own counsel and if the tank is amazeballs, I suppose you'll be fine, but I wouldn't leave it filled like that for any length of time and I would not do that at all, given the cost of a flood later in my house. Don't want to lecture you but I don't think you'll find anyone who would tell you "that's no problem". I hear what you're saying but if you want to test more, I'd advise you to level the tank in the test spot.

A lot of the aftermarket overflows are kinda not so great, IMO, and other's seem to share that opinion.

I like my Synergy Reef Shadow v2 a lot, though apparently it's noisy if you're pushing a lot of water (I'm not). Waiting on a Modular Marine, that I have high expectations for my use case. But, I hear you.

Trever · Mar 23, 2021

Sorry, I'm an editing maniac. Bad habit.

JCM · Mar 23, 2021

JumboShrimp said:
I didn’t want to add to your problems and tell you the bigger problem: When you have it hooked up, cut off your pump. Check to see if the water ever stops trickling into the overflow box!!? In the end, I had to slobber my tubes with silicone, because when I complained to Fiji that water kept leaking into the tubes by bypassing the seals, and all they did basically was shrug and say, ‘yeah, sometimes the tubes don’t fit tight inside the bulkhead.’ To me it is a design flaw that can lead to a sump overflowing, if the tank is big enough.

Haha yeah, the garbage bulkheads were my first complaint. I bought a new nut and seals and that seems to have fixed that issue. They certainly won't get a glowing recommendation from me.

JCM · Mar 23, 2021

Trever said:
The stand didn't rock? Umm.... ok. That's a low bar? You have what looks like a lot of water pushing against the sides very unevenly. Keep your own counsel and if the tank is amazeballs, I suppose you'll be fine, but I wouldn't leave it filled like that for any length of time and I would not do that at all, given the cost of a flood later in my house. Don't want to lecture you but I don't think you'll find anyone who would tell you "that's no problem". I hear what you're saying but if you want to test more, I'd advise you to level the tank in the test spot.

A lot of the aftermarket overflows are kinda not so great, IMO, and other's seem to share that opinion.

I like my Synergy Reef Shadow v2 a lot, though apparently it's noisy if you're pushing a lot of water (I'm not). Waiting on a Modular Marine, that I have high expectations for my use case. But, I hear you.

Sorry I wasn't trying to argue, I appreciate the input. Pressure on the glass is only a function of water depth in this situation (good ol Bernoulli). If that side can't handle an additional inch of water for an hour then I don't trust the tank period. I'd rather it bust now rather than later (in the house) with an inch less of water. A much bigger problem would be twist, which would be caused by a stand that rocks or If the tank didn't sit flush on the stand around the perimeter. That would absolutely cause cracking.

I agree aftermarket overflows seem suspect. I looked at the Synergy then read a bunch of bad reviews. I wanted a modular marine but seems they aren't producing them at the moment.

Trever · Mar 23, 2021

The manufacturers claim the slow leak like that is not an issue because it can take 24+ hours and if that's the case, you've got bigger problems. For me, it's more like: better make sure it's ok if I'm out of town for a week! Everything dying AND my house flooding is worse than everything dying (never thought I'd say that).

IMO it is a design flaw with these style overflows. The weir is supposed to set the water level under all circumstances, not some hidden bulkheads. So says I!

It looks and sounds like you just need to dial back the flow and you'll get the water level you intended. Whether you'll then get the flow you intended, is another question.

JCM · Mar 23, 2021

Trever said:
The manufacturers claim the slow leak like that is not an issue because it can take 24+ hours and if that's the case, you've got bigger problems. For me, it's more like: better make sure it's ok if I'm out of town for a week! Everything dying AND my house flooding is worse than everything dying (never thought I'd say that).

IMO it is a design flaw with these style overflows. The weir is supposed to set the water level under all circumstances, not some hidden bulkheads. So says I!

It looks and sounds like you just need to dial back the flow and you'll get the water level you intended. Whether you'll then get the flow you intended, is another question.

I agree, I think this style of overflow is inherently flawed. Still better than the giant internal box this tank had that took up 1/4 of the water volume.

The house flooding is my worst nightmare, if the tank busts now so be it. I just consider this a test haha

I hope you're right. I'm only using the Mag7 to test because I had it in storage. I dont mind using a smaller pump, I actually have an Eheim 1250 I was planning to use but was nervous it wasn't enough flow. Most of the flow will come from a couple of mp10's anyway.