How to start the overflow.

[JohnS]

Very interesting thread. Thanks all for the info so far.

I'm thinking about using something like this to tie my 20g qt into a 30g garbage can (effectively giving my new fish 50g). Since I'm going with a smaller application, do you think I could build it with smaller diameter PVC? or would it be smarter to redesign it using fewer drains/ports? I'll probably use my Mag 7 as the return ph.

Any thoughts?

 

[easyian]

It could easily be built with smaller tubing or redesigned to have one siphon tube. I was thinking of resizing it myself but I have a whole bunch of one inch tubing and such left over from installing my underground sprinklers that I just stuck with the one inch.

In effect you could definitely cut it in half.

 

[Phyl]

Easyian, you gotten this thing primed and running yet? We're building ours now and are quite curious how we're going to get this started. We were hoping that you would have paved the road before us! LMK if you know what you've learned.

Thanks!

 

[easyian]

After building this thing and trying to start it I found it was a royal pain to get the siphon started. So my solution was to add a brass shut off with compression fitting on it to get rid of the air. It is just an inline shutoff valve with 1/4" compression fittings on either end. I left the fitting off one end and screwed it into the very top of the siphon tube crossover and added a short piece of 1/4" tubing so I can suck out the air. Now it is a breeze to start. Here is some pics to show you what I did. If you would like to see more pics of the build up PM me and I can send you some. I was planning on doing a full DIY in it when i got it running.

 

[Phyl]

We managed to get our syphon started with a lot of suction and 4 hands (and a couple mouthfuls of thankfully tap water), but when the water stopped, the syphon broke and it wouldn't restart when we started the pump again. Could you give me the dimensions on your verticles? I think we may have something off there. It looks like your tank part is shorter than your outside section, is that the case? I'm also a little unclear as to how you have the valve mounted at the top. Any extra details you could provide there would be greatly appreciated!

 

[easyian]

Phyl
Unfortunatly I PMd you before I read this post. But here are the dimensions I used.
The siphon tube you see in the tank are 5" long not including the elbows and tees then the down tubes on the back side are 8" long. The up tubes are 6".

First pic two up front 5"
Second pic two longer ones 8" three shorter ones 6"

 

[easyian]

I dont know if the pics i pmd worked

 

[Phyl]

Great! Thanks for all the information. I'll let you know how we do tonight when we adjust the lengths and we glue it together . Our in-tank legs right now are the same length as our back lines. The picture of the valve is great. What do you figure the theory is behind that spout that goes up that is open? That makes so little sense to me! Seems like air would get into the system through that when you shut it off. We actually covered ours in an attempt to get it to keep running (before I posted here) to no avail.

 

[jsoong]

What do you figure the theory is behind that spout that goes up that is open? That makes so little sense to me! .

That is to prevent a 2nd siphon from being established between the back of tank loop & your drain line to the sump. <Am I making sense?>. In case of a pump failure, a siphon in the back of tank loop will drain off the "real" siphon tubes & break the siphon. So the open tube is to prevent that.

FYI, the durso system would have this open tube capped & a small hole drilled into the cap. That makes the back loop into a partial siphon. This greatly reduces the noise of the overflow & still provide for a siphon break at that location.

BTW - keep the results coming on this project! I am waiting for you guinea pigs to work out the kinks before I build mine! <THANKS!>

 

[easyian]

I agree with jsoong. If that vent wasn't in there then the siphon would not break when the level got to the line you want it to stop at. That way it would suck the water out until the in tank overflows were exposed. Im not 100% sure but when the siphon did break i dont believe that it would start again when you wanted it to.

 

[bound_for_obx]

does anyone have any flow rates yet?

 

[jsoong]

Im not 100% sure but when the siphon did break i dont believe that it would start again when you wanted it to.

I think that the siphon will be maintained in case of a power out & will restart when the power comes back on. However, I see a possible problem. On your picture, it looks like the sump exit point is higher than the tank intake strainers? The water level in the tank will need to be higher than that level ( and quite a bit higher than the level of the strainer) before the siphon will flow.

This is like what I have now (although I made it with a back overflow box). The water level in the tank end up controlled by the sump outlet level, plus a bit extra "head pressure" to drive the siphon. I find that it is a PITA to adjust, as the water level will change with any change in return pump flow, back pressure from the wet/dry, etc. <That is one reason I want to make a new one>.

The system I am planning <see picture> will have the sump outlet between the strainer & the bottom of the in-tank loop. I think this way, the water level is controlled by the strainer height, and the driving pressure through the siphon is fixed so I'll have constant flow.

Any one see any flaw in the design?

 

[easyian]

The reason that the rear is higher now is because I havn't put the strainer pieces into place yet. The rear tubes are at the waterline I wanted in my tank. It keeps the water just above the glass line so you do not see the top of the water while viewing from the front.

Here is what it will eventually look like. Pic courtsey of Craig's DIY Reef Ideas

 

[easyian]

Phyl hows the overflow working?

 

[Phyl]

We haven't finished it yet. We have the airtube thing installed, just need to glue it together and test it. I'll definitely post back when I have some news!

 

[Kasakato]

Do you think that would work with 1/2" PVC pipes? I want a super low flow rate, for my 20g tank.

 

[easyian]

I dont see why it wouldn't work you would just have to recalculate some of the measurements to work with your tank and the size of the PVC. I havn't been able to afford my pump yet so I havn't been able to let anyone know how well it works on the tank. It worked well hanging off the side of the laundry tub with the tap on though.

 

[Verbalkint]

Just curious, as I have not seen any real numbers yet...

Using the 1" PVC, what are the lengths of the straight parts?

For instance, the length of the strainers is cake.. Determined by how much water you want in the tank.

But, the other straight parts... How long should those be?

 

[jsoong]

I think the length is up to you. It is a compromize between looks & function.

My thinking is expressed in the drawing I made few posts back. You need to have the sump outlet between the intake strainer & the bottom of the in tank loop. For maximum flow, you want as much height between the intake water level & the sump out. If looks was not a concern, you would want to have the in tank loop down to the tank bottom & site the sump out almost at the bottom. This is like a drilled tank's arrangement, and will give you something like 20" of head pressure to drive the siphon - that should give great flow rates & may allow for smaller tube size. But I think a big thing like that would be ugly!

I am waiting for some flow numbers to see how short I can make the in tank loop & still get good flow. I read few years ago a site that has a calculator on head pressure & flow rate through siphons. I am trying to find that again to give me some guide on height needed. If all else fails, I'll have to experiment in the bathtub.

 

[Kasakato]

About how much PVC did you use? I was going to go to HD anyways so I guess I could get this at the same time. Also how much is it?