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Reefaholic
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Discussion Starter · #1 ·
I just got my parts delivered today and going to add my first fish tonight after setting up the plumbing. My question:

If I am going to have my returns too far under the water, or at heights that wont be predictable... how do I make siphon breaks in my return line? Just drill 2 holes about a half inch below the water surface? Do they need to be a certain size? Do I need more than 2? I have never had to use a siphon break before.
 

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You are correct.
Just one hole should be ok, ( for each return line) just big enough to allow enough air in to break the flow.
Start small and see what happens.
another thought is to have the hole pointing down into the water just in case you have a lot of pressure from pump, you don't want little fountains shooting up out of tank
 

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You are correct.
Just one hole should be ok, ( for each return line) just big enough to allow enough air in to break the flow.
Start small and see what happens.
another thought is to have the hole pointing down into the water just in case you have a lot of pressure from pump, you don't want little fountains shooting up out of tank
+1, I would experiment a lil here. also no check valves. I installed one when I redid my return and it was faulty within 2 months.
a second hole is meant for an emergency incase a snail, algae or something else is blocking the first.
 

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Reefaholic
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Discussion Starter · #4 ·
Ok, so my plan is to have my return come over the back and then down about 6" to two rotating water deflectors. Assuming the worst and that power shuts off while BOTH are at the down position the siphon break hole will be enough to stop it? Pretty basic question, I know... but I want to make sure my plan does not have a flaw I am overlooking.
 

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Reef Junkie
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No less than two holes and no smaller than 1/8" however it will inevitably fail. One small hole as suggested is just asking for a flood.

The better option would be to keep your returns just a hair below the surface and design your sump to handle the back siphon. You can put a few holes in as well but I wouldn't count on them. My return is at the surface - low enough to not splash but high enough that as soon as the pump goes off it sucks air and breaks the siphon.

At 6" below the worst assumption would be that the holes are all clogged and it back siphons your tank down to that depth and you have to break out the shop vac.

The glaring flaw I see is wanting to use the return for anything more than bringing the water back up. Flow should always be achieved elsewhere. :)
 

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Reefaholic
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Discussion Starter · #8 · (Edited)
Here is a pic of what I plan (attached)

So I can either put siphon break holes, where the green X is, or another outlet that can act as a siphon break hole. The purple line is the expected water line, the dark blue is the rotating deflectors, the light blue the direction of flow from what I have in mind.


I will have 1600GPH powerhead on each side, but want some opposing, random flow against it and think this would be the best option besides getting an actual sea swirl. I want to maximize all flow options available using the least amt of electricity... I don't see how that is a flaw :)

These are the deflectors I want to put on.
 

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Reefaholic
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Discussion Starter · #10 ·
the flow within the dt isn't the flaw, its the flow going through your sump. but that also depends on how your sump is setup. settling tank vrs whatever else.

Here is all I have for my sump right now, took these last night and not at home.

Skimmer section (hardly fits lol)



Return section (to the right after the baffles)



The return section is just a 12x12 section for the return pump. The return pump is a 800GPH pump... so roughly 600GPH actually coming out. The water deflectors can handle just under that so I was thinking of doing a siphon break, or another outlet to distribute some of the flow and also have a safety for back-siphon. My sump is just a 20 gallon so having this back-siphon is a real, legitimate fear I am having... so by saying it depends on the flow through my sump you are referring to how much room I have for error, the answer is very little.
 

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that's a nice skimmer there :) I think im getting one next month, either that or the month after.. the best siphon break I can think of are the drilled holes as described above. everything else I have in mind gets a lil too unsightly and probably not needed.. such as drilling a hole at the top of the return, silicone a airtube into it and run the other end of the air tube to your min waterline. once air hits the airtube siphon breaks, but that's pretty much the same as drilling a hole.
 

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The main Issue I see potentially, and mind you I am not familiar with the hydor flo unit is that it appears to work on pressure and flow through volume to create the rotation effect. Depending on how much back pressure the device creates it may be possible that a couple of 1/8" holes in the line , just below the surface might allow enough water to leak out there reducing the rotators efficiency.
I don't remember off the top of my head how big your display and sump are but the whole idea behind the siphon break just below the normal water line is in the event of a power off water can only backsiphon till it hits the holes in the line allowing air to enter and break the siphon effect. If the holes are say a half inch down, not much water will siphon back into the sump, without the siphon break and the rotator 6 or more inches below the surface that is a lot of water to add to the sump before it stops from sucking air
 

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that's a nice skimmer there :) I think im getting one next month, either that or the month after.. the best siphon break I can think of are the drilled holes as described above. everything else I have in mind gets a lil too unsightly and probably not needed.. such as drilling a hole at the top of the return, silicone a airtube into it and run the other end of the air tube to your min waterline. once air hits the airtube siphon breaks, but that's pretty much the same as drilling a hole.
I see where you are going with that PS but in my experience overcomplication adds further worries, although I can see that working if you could get a hard plastic that would snugly fit inside the return tubing if using hose, add a drilled and cemented in elbow barb that would accept a piece of airline tubing and fix it just below the water line
 

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Reefaholic
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Discussion Starter · #14 ·
The main Issue I see potentially, and mind you I am not familiar with the hydor flo unit is that it appears to work on pressure and flow through volume to create the rotation effect. Depending on how much back pressure the device creates it may be possible that a couple of 1/8" holes in the line , just below the surface might allow enough water to leak out there reducing the rotators efficiency.
I don't remember off the top of my head how big your display and sump are but the whole idea behind the siphon break just below the normal water line is in the event of a power off water can only backsiphon till it hits the holes in the line allowing air to enter and break the siphon effect. If the holes are say a half inch down, not much water will siphon back into the sump, without the siphon break and the rotator 6 or more inches below the surface that is a lot of water to add to the sump before it stops from sucking air
I have thought of this too. The back pressure created should not be enough to reduce efficiency. These rotators can work with as low as 85GPH each. I highly doubt a couple small holes would cause it to go under that. This is why I was also thinking of getting a T and having an opening just at the water level with a ball valve on it. This would be under the center brace so out of the way, it would also ensure there was a more consistant flow getting to the rotators.
 

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Reef Junkie
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Have you run your return pump and plumbing through the head loss calculator? You lose a lot more than you'd think with head height, elbows, T's etc. Probably not less than 85 but quite a bit.
 

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Reefaholic
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Discussion Starter · #17 · (Edited)
Have you run your return pump and plumbing through the head loss calculator? You lose a lot more than you'd think with head height, elbows, T's etc. Probably not less than 85 but quite a bit.
I have, I did not find the same pump I have, but a similar one and came up with something like 575, or close to that. It was just under 600.

I think I am going to go with the additional outlet at the top surface of the water and use a valve to dial the pressure back.
 
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