Silent and Failsafe Overflow System

[uncleof6]

Been running this system for over a year now. It's quiet that is for sure. I have a peninsula tank 2x8 so my over flow is 24" across with no teeth. If I had to do it again I would definitely add teeth to my over flow. Snails are always finding their way into the overflow box and going down the drain. I had to install a net on the drains to keep the snails out of the pipe. Another issue is fish, they get sucked into the over flow and I've lost at least 5 fishes now. I see the benefits of having no teeth to increase surface skimming but the fish lost outweighs the benifets if you ask me. These were not cheap fishes either. Rhomboid, platinum clown, chevron tangs and a few others. Unless you can put a net in front of the overflow, get teeth.

Many are coming to the realization of the problems with putting teeth on the "weir." Because of the efficiency loss that teeth create, which affects both organic removal and gas exchange, other solutions are more appropriate.

Fish live under water. They do not like to leave the water. To go over a weir, they have to leave the water. Since it is against their nature to do so, you have to look at the real reasons they do so, not the "take the responsibility off of the hobbyist" reasons that are the most popular (that "critter" has a reputation for jumping.") The two top reasons fish leave the main tank are harassment/aggression and poor water quality. These are both the responsibility of the hobbyist.

The teeth look cool, and came out as a marketing gimmick to facilitate selling equipment. If it had teeth, hobbyists were more inclined to buy the product, because "how could such a thing be a waste?" Problem is the teeth will not stop fish from jumping into the overflow and certainly won't keep snails out of anything. No one is perfect, and occasionally I have a critter decide the overflow looks inviting, both with toothed weirs when I used them, and without. Most have wound up swimming happily in the sump, 1 got stuck in the drain and died. I think that, considering the number of system I have running, and the amount of time I have been at it, the attrition rate is not sufficient to determine a preference for a toothed weir over a flat weir.

I think that if this is really a genuine concern, and not merely a case of folks repeating what someone else said, covers on the overflow, that allow the free flow of water would be a better solution. This would put the needs of the system first, and solve the issue of a "high" attrition rate, if ones system suffers such. Though, I do think that better husbandry and a better knowledge of the critters one keeps, would go a very long way on its own. I solved the snail issue by removing snails from my systems, and don't introduce them intentionally. I consider them to be pests.

 

[mike810]

Many are coming to the realization of the problems with putting teeth on the "weir." Because of the efficiency loss that teeth create, which affects both organic removal and gas exchange, other solutions are more appropriate.

Fish live under water. They do not like to leave the water. To go over a weir, they have to leave the water. Since it is against their nature to do so, you have to look at the real reasons they do so, not the "take the responsibility off of the hobbyist" reasons that are the most popular (that "critter" has a reputation for jumping.") The two top reasons fish leave the main tank are harassment/aggression and poor water quality. These are both the responsibility of the hobbyist.

The teeth look cool, and came out as a marketing gimmick to facilitate selling equipment. If it had teeth, hobbyists were more inclined to buy the product, because "how could such a thing be a waste?" Problem is the teeth will not stop fish from jumping into the overflow and certainly won't keep snails out of anything. No one is perfect, and occasionally I have a critter decide the overflow looks inviting, both with toothed weirs when I used them, and without. Most have wound up swimming happily in the sump, 1 got stuck in the drain and died. I think that, considering the number of system I have running, and the amount of time I have been at it, the attrition rate is not sufficient to determine a preference for a toothed weir over a flat weir.

I think that if this is really a genuine concern, and not merely a case of folks repeating what someone else said, covers on the overflow, that allow the free flow of water would be a better solution. This would put the needs of the system first, and solve the issue of a "high" attrition rate, if ones system suffers such. Though, I do think that better husbandry and a better knowledge of the critters one keeps, would go a very long way on its own. I solved the snail issue by removing snails from my systems, and don't introduce them intentionally. I consider them to be pests.

In my cube I had teeth on my over flow. It wasn't a been animal but that is irreverent. With the teeth on the over flow, I never had issues with snails climbing into the over flow box. They would climb to the top and once they hit air, they stop. In the 4 years I've had the cube, I only had one fish make it into the over flow and down the drain. That was only because the watchman goby was so tiny it literally slipped in between the teeth.

Now with this current smooth over flow. Snails are not so much of a problem for me anymore, in fact they are kind of welcomed in my overflow. Since putting a net on the drain, I don't worry about them going down the drain. Instead they clean the overflow really nice.

The only issue is still the fish. Some like you might never experience a fish getting into the over flow. Me on the other hand, I have watched the fish get sucked in countless times. Every time I would have to turn off all the pumps to rescue the fish from certain death. I have completely lost count of how many times I've had to rescue fish. This is not including the fish I have actually lost because I wasn't home to rescue them in time. Every time I look at the tank, I make it a habit to check the over flow for fish. I check the over flow at least 3-4 times a day, once in the morning and once in the evening when I get home from work, then any other time I look at the tank.

I do not believe my water quality is the issue. I parameters once a week and they are spot on, I have a lot of sps in my tank. In my previous post I mentioned losing a chevron tang, at the time I had no tank mates remotely big enough to punk that tang yet it made it into the overflow. I have screens over my tank so there is only so much space between the top of the overflow and the screens. They are not jumping into the overflow, they are getting sucked it. Watched it happen too many times to put the blame on tank mates or water quality. They simply swim too close and boom.

This is simply just my experience with the smooth over flow that I am sharing with others. I would get teeth if I ever upgraded.

 

[thejuggernaut]

So do they jump in to the box, or do they just slip over the top?

 

[mike810]

So do they jump in to the box, or do they just slip over the top?

They don't jump, they slip over the top.

 

[uncleof6]

Some will jump, you have to actually see it happen to believe it. Fish don't normally hang around the surface of the water in nature (some species like flying fish and mammals do,) but generally reef species are not surface feeders by nature. If you train them to do so by surface feeding them, they will be more likely to hang out at the surface of the water and get sucked into the overflow.

Like I said is a question of knowing your critters, and husbandry skills that will keep the fish out of your overflow. I also added that a cover can solve most issues without the use of teeth. You also understand, that some of us that have no issues with fish in the overflow, are running full length overflows with very thin layers of water going over the weir. This is not at all inviting to fish. There is more to the methods than can be seen with a quick glance.

 

[mike810]

You also understand, that some of us that have no issues with fish in the overflow, are running full length overflows with very thin layers of water going over the weir. This is not at all inviting to fish. There is more to the methods than can be seen with a quick glance.

You know uncle, you bring up a very good point about the height of the water level going over the over flow. I guess people with thin/flat water going over the over flow wouldn't have a problem with fish. For me, the water height going over my over flow is close to half an inch high. I guess that is my issue when it comes to fish getting in. There is enough space from the top of my over flow to the water line that lets fish get sucked in easily.

 

[Floyd R Turbo]

Mike, I run a tank in similar fashion - end overflow weir, 16" wide, 3000 GPH over it, 3/4" water height over weir. I have a Flame Hawk that refuses to stay in the DT so he lives in the sump now. He also swims up and over the baffles in the sump all the time (to hide from me). To do a notched weir with flow that high is where you run into difficulty, because you essentially have to use a 50% flow reduction factor due to the teeth, meaning that if you do 1/4" teeth every 1/2", then make the overflow wide enough so that the sum of the notches equals you current overflow width, then apply 50% reduction. Which means that you need 2x as many notches to get the same flow.

So if you have a 20" wide weir, you would need an 80" wide box to get the same flow and same water level (80" wide with 1/4" teeth every 1/2" = 40" effective openings, reduce by 50% = 20" equivalent weir)

The other option is to use the 1/4" or even 1/2" aquarium DIY lid netting from BRS or the like to create a screen that doesn't inhibit flow. Problem with that is, it's just another thing you have to keep clean.

 

[woodnaquanut]

My OF has about 1/2 inch of water above it. I have 'gutter guard' on the inside of the OF box. So far (1.5 yrs) I haven't had any fish go over it. Of course I only have three fish that could possibly fit thru the gutter guard.

 

[rickztahone]

My OF has about 1/2 inch of water above it. I have 'gutter guard' on the inside of the OF box. So far (1.5 yrs) I haven't had any fish go over it. Of course I only have three fish that could possibly fit thru the gutter guard.

Do you happen to have a pic of it?

 

[mike810]

My OF has about 1/2 inch of water above it. I have 'gutter guard' on the inside of the OF box. So far (1.5 yrs) I haven't had any fish go over it. Of course I only have three fish that could possibly fit thru the gutter guard.

+1. Pic please

 

[uncleof6]

My OF has about 1/2 inch of water above it. I have 'gutter guard' on the inside of the OF box. So far (1.5 yrs) I haven't had any fish go over it. Of course I only have three fish that could possibly fit thru the gutter guard.

I would prefer to see people do that, than run teeth on their overflow. (As if what I prefer has anything to do with anything.)

 

[Reefer PT]

Question, I have only 2 holes in my overflow box and can't fit another. For the dry safety line would it be ok to add a third bulkhead to the back of the tank with an upturned elbow and stand pipe and suction screen to just above the water level without an overflow box? Sorry if this was answered before I only read the first few hundred posts on this thread.
Dave

 

[uncleof6]

Question, I have only 2 holes in my overflow box and can't fit another. For the dry safety line would it be ok to add a third bulkhead to the back of the tank with an upturned elbow and stand pipe and suction screen to just above the water level without an overflow box? Sorry if this was answered before I only read the first few hundred posts on this thread.
Dave

This system is not recommended for a tank with a small corner overflow. You will be way ahead to just install a "herbie" type system, with the siphon on the smaller of the two holes, and dry emergency on the larger of the two holes. (If there is a difference in hole size.) Configuring the standpipes/drain lines differently, for instance a hole out of the back of the tank, will cause them to behave differently, making the resulting system unpredictable.

 

[thejuggernaut]

Question, I have only 2 holes in my overflow box and can't fit another. For the dry safety line would it be ok to add a third bulkhead to the back of the tank with an upturned elbow and stand pipe and suction screen to just above the water level without an overflow box? Sorry if this was answered before I only read the first few hundred posts on this thread.
Dave

You can't fit a line through the bottom of the overflow, but you can through the back of the tank. That is how I had my old tank, except I didn't put anything on the bulkhead through the back. I enlarged one of the bottom bulkheads so the were both the open lines, then drilled the hole through the back (about 2/3s the way down the tank) for a 1" bulkhead for a full siphon and i calculated my flow at 900 GPH and it was completely silent.

 

[Reefer PT]

This system is not recommended for a tank with a small corner overflow. You will be way ahead to just install a "herbie" type system, with the siphon on the smaller of the two holes, and dry emergency on the larger of the two holes. (If there is a difference in hole size.) Configuring the standpipes/drain lines differently, for instance a hole out of the back of the tank, will cause them to behave differently, making the resulting system unpredictable.

So all of the warnings about the 2 line system should be ignored? I know I will only be putting 600gph through the overflow but I am still nervous.

 

[thejuggernaut]

So all of the warnings about the 2 line system should be ignored? I know I will only be putting 600gph through the overflow but I am still nervous.

Ran one for years before I eventually turned up the flow a little and installed the third back bulkhead like I described above, but I never had snails, I hate those little ugly things crawling all over my glass. Plus most people don't run a true Herbie. They incorrectly use the dry emergency as the open channel and it always handles a little flow. The whole point is to get the drain completely out of the water column so nothing will climb up in it or get sucked down it to clog it. The Herbie does require more tuning, both initially and in the future as algae coats the pipes and you get small changes in flow. I believe most floods are due to neglect, and if you take 3 seconds to inspect your system daily, then you can probably avoid most issues and your risk is manageable.

 

[uncleof6]

So all of the warnings about the 2 line system should be ignored? I know I will only be putting 600gph through the overflow but I am still nervous.

As juggernaut was saying, the warnings about the 2 pipe siphon system, or "Herbie," concern the use of a wet secondary, or a "trickle of flow" in the dry emergency. The idea behind the use of a wet secondary with the "Herbie" is to take care of the inherent instability of the system, caused by moderate variations in flow rate. The "Herbie" is not supposed to have a wet secondary, and the wet secondary was not used till after the publishing of Bean's design.

The "Herbie" will self adjust, without the use of a wet secondary, due to changes in pressure head (water level,) but the band width is rather narrow, limiting self adjustment to "small" variations. Under normal circumstances, it should not require constant re-adjustments, rather "periodic" adjustment, the interval of which will vary from system to system. So what should not be ignored is the safety risk involved with running a wet secondary, as the "inherent instability" is not great enough to justify the flood risk.

I have seen only one instance where the variation was causing a problem (near flood or near famine) but the problem was the pump output varying, for reasons we never did figure out for sure. I suspect that constant need to fiddle with the adjustment, would be due to not getting it set in the "sweet spot" balancing the drain capacity with the pump output. For that reason I recommend gate valves over ball valves to get a finer adjustment.

 

[uncleof6]

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[uncleof6]

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[adova]

I have been noticing that the water height in the overflow box changes over time without any adjustment to the valves. The variable that does change (as I am still setting up) is the sump level where the return pump is located.

Can the sump level affect the pump output and hence the overflow water height?