Opinions appreciated: check valve vs anti-siphon holes in overflow returns
 

I am looking for input from seasoned users who have either check valves or drilled return lines.

I have read, and read, and read, for 5 months online. I've seen horror stories about check valves failing. I've also seen the same said about drilled holes due to snails and such.

I have flow-tested my system, and am happy with it so far, but would like the option of placing my 3/4" loc-line nozzles either below the surface or just skimming.

I guess that there is danger either way. Blockages being the prime concern.
Personally, locline just below the surface is my choice.

No offence, but you're not giving me a long-time user experience with your reply.
I'm looking for user responses with long-time experience.

Should I use a union check valve or not?
I don't want to drill my lines.
What's your experience?

I've been using a check valve for a year and a half, no issues.

How do you know how long this person has been in fish keeping.

I guess I won't offer advice.

Just removed the union check valve yesterday and run the nozzle just below water surface. Reason for removing is every time I turn off and on the pump it making stupid noise.

I drilled 2 small holes just below the waterline on each of my locklines, have had no probs for over 2 years, cleaned them @ a month ago and all holes were still flowing.

lol dont you know? online post counts are obviously an accurate representation of how much experience you have

I use both.....my check valve is on a union and I have two.....I swap them out very so often for cleaning....

Whats the matter with his response?

I have done my tanks that way for 40yrs. Never have I ever used a check valve. My returns have just been under the surface, with the sump holding any back flow.

I also drilled a 1/8th. in. hole for back up but as mentioned, my systems would be fine without.

I liked to drill them om an upwards angle so the water sprayed straight down. Also on the backside, where the piping came over the top. I found snails could not bother it as much when between the pipe and the glass with not much room.

Only snail problem I have had was one the cover the hole partially and the water squirted in the air. That was corrected by the above angle and placement of the holes.

Having the return just below the water line is still the best solution as was said. If its under far enough that back flow will flood the sump, {for whatever reason I,m not sure},then a check valve is the only solution. Although many have run them with great success, I have read many stories of floods from their failure.

most check valve failures are due to the seals getting schmengy....I always recommend that people buy two and swap them out for cleaning......that and make sure that your sump can handle any back siphoning that may happen in a "worse case" scenario

Good advice.

I've run both anti siphon holes and check valves on tanks in the past. Both are methods equally prone to failure and there will always be a chance they fail one time when you're unprepared. Maintenance will reduce the risk but not eliminate it completely.

I prefer the KISS principle.. On my tanks I run now I keep enough space in my sump to handle the backflow. The higher the output nozzles the less backflow volume you need to account for. Plus, having output nozzles near the surface has the added advantage keeps better surface agitation.

This topic really irks me. It is beyond my realm of mental capability to understand why someone would design a system that could possibly allow an overflow during a power outage.

Personally, I have no use for a check valve. I think they are a waste of money. I would rather design my sump to accommodate the back flow (who fills their sumps more than 60% anyway??), and design the return plumbing in a way that only an inch or two of water will back flow. To me, relying on a check valve or anti-siphon holes to keep my floors dry is absurd. If the system is designed in a way that the sump won't overflow regardless, then it makes the check valve and anti-siphon holes completely superfluous.

When designing the system, measure from the running water line to the top of the opening of your return line (where the siphon will break). Use an online volume calculator to figure out how many gallons will back siphon. Make sure you include any other volumes of water that may siphon (like a compartment/overflow box that has some silly design). Then add 25% for safety. Then measure from the water line in the sump to 1/2" below the top of your sump. Figure out that volume. If the available space in the sump is more than the back flow volume you're good to go. If the available volume in the sump is less than the back flow volume you need to redesign to make space for the volume or to reduce the volume backsiphoning, and I don't mean to using gadgets like check valves! Redesign by using standpipes, baffles or such in the overflow boxes, or by raising the return opening to make the siphon break higher.

If all else fails, you just can't seem to figure this out then fill your tank up outside with the hose and do a freshwater test run. :D

+1 to Myka. Very well explained.

I agree with Myka, the need for siphon breaks or check valves is a result from bad design. I think the majority of experienced people will agree you shouldn't rely on such things. However you may want to add them to prevent full back back flow all the time but your system should still be able to handle the back flow if the breaks or valve fail. If this were the case check valves would be a better option than break holes as they require more maintenance being that they are often plagued with algae growth.

In my case it's not bad design..... I do my water changes by siphoning from the display most of the time.... Siphon break holes and check valves help keep more water in the display so I can siphon out more crap....

Agreed provided they aren't actually needed.

I do lol. But only because my last baffle is too high so if I keep water level to low I end up with bubbles in dt. But my sump still holds any flowback

I did all of the above, I drilled a small hole in my return line, I installed a george fisher check valve, and my sump has enough capacity to hold the back flow, if the check valve fails and the anti-siphon hole gets plugged.
Why only have one safety in place when I can have multiple.

+1
Also don't forget the other end of things, Make sure your display can hold the volume of water your return pump will push up if the drains ever did become blocked!!

I do this too, but in my case, after siphoning 10 gallons out I turn the return pump on the empty the sump so I can remove another 5 gallons from the display without the corals being out of the water very long.

I have an "emergency" drain for just that purpose. :D

I agree. Although there is a difference between redundancy and superfluency. Knowledge in cause and effect will define the difference.

this is what i do too:)



agreed, since most return pumps arnt the main source of flow most just use them for surface agitation, i like that when i need to the high loc lines are good to point towards my frag shelf:P

+1 on emergency drain

I have 2 overflow with with one emergency.

Everything that myka said makes sense. I don't use check valves on my system but I drilled holes in my returns and I make sure that they are cleaned every so often to prevent plugging.

Jeez, did I not say that also. I added the anti siphon just for back up.

Yeah but you didnt put it in fancy bold letters lol:p

Oh ok, sorry. :lol:

No siphon break holes or check valves here, just room in the sump for the back flow.

+1 for me

My apologies for my unknowing opinion.

Wow, I should have checked in yesterday

All I meant was ensquire gave no reference as to how long the loc-line had been in use.
My reply wasn't meant to imply anything else.

I'd like to thank Everyone for their input. I never imagined I'd get this much feedback.

With the limited # of responses to using a check valve, and the thoughts on it fouling etc, that option is off the table.

I am attempting to get some surface flow from the loc-lines. Because of the way I currently have them, there is the chance they can be bumped quite low below the surface, allowing way too much volume to back siphon. I will have to re-think the routing.
This is how they sit and now you see why I originally posted these questions.

http://i749.photobucket.com/albums/x...d/DSC00911.jpg

I agree whole-heartedly with the idea of laying out the lines so no valve or anti-siphon holes are required.
I'll have to attempt to shorten the lines and it looks like I'll lose the surface flow I was looking for.

I'm going to try this. On the right of the overflow box is a 'Y'
It and the nozzle pointing forward are twisted to their max and cannot point down any farther. This nozzle will be the siphon break
The eggcrate cover won't fit if they change position so it'll alert me if I bump it during maintenance or WHY
Now I can still have the surface flow I was looking for
Hopefully this will eliminate dead spots on the surface corners

http://i749.photobucket.com/albums/x...urnNozzles.jpg

I use both.

Check valves work great, but over time the seals dry due to the salt in our tanks.

I shut my return pump off for target feeding so I get to check them regularily to ensure function.

I replaced them recently... once in 1.5 years.

The siphon holes are back up as in extra space in the sump. You can't be too careful.

Thanks, that's what I suspected
I'll try my latest configuration and am still contemplating drilled holes, but only as a backup.
I have a lifetime subscription to Back-up magazine :biggrin: but am also trying to go with the KISS method.
Because I haven't tested my system yet with salt, I have no idea what kind of micro bubbles I may end up with due to my current config. This is why I'm leaning towards no holes.
All I can do is try it and worst case I replace the drilled pieces, right?

Thanks for clarifying that
I used a Y like you did here, but used the flare end thinking that it was less likely to get pushed too deep.
Drilling a couple of holes for back up is never a bad idea, and as you said, the drilled segments can be replaced .
Things are looking very clean, very well set up system.

Thanks for your input and understanding Mike

It's so easy to just type away here, but the true meanings of our posts obviously can be taken the wrong way too easily.
This is what sucks about not being face to face. Hence the importance of watching what we type.

Maybe this is why everyone uses 'lol' too much?
Anyway, I will be more careful with my posts :wink:

As will I "LOL" :biggrin: