Simple Physics Question.

[nfored]

sorry my error........without the cap what is the problem ??

if it is not enough flow.......maybe a larger pipe is the answer

I have come to the same convulsion, but I will let my macgyver trick run for a few weeks and see how it works. I am really impressed with it so far. By putting a small hole with an airline into the cap and having the airline run from there into the tank, I get the best of both worlds. basicly sealed when full of water and unsealed when the water level is low. I may move to 2 inch drain, if I have to.

 

[JoelB]

Hi nfored,

Your problem is this.

Without a cap your water above the bottom of the T overflows to the drain like a weir. It simply topples over with no influence from the water around it, no suction or anything.

With a cap, there is siphon power. The weight of water in the drain half of the pipe falling down is all pulling more through.

Capping it should cause the tank to drain all the way to the bottom. It should therefore not be capped. Trying to vary the size of the hole may help a little but it is not a proper solution in my opinion.

As you have it, if your uncapped drain allows the water to rise to above the top of the T, then it can't keep up and should be bigger (or use a different setup). Otherwise, it's fine.

 

[Tigerdat]

I think you are asking for problems. If that 1/4" airline ever clogs, or restricts the air/water even a little bit it probably won't be enough to break the siphon. Remember its sucking water through it too so it can easily get clogged/restricted. All that has to happen is the 1/4" hose get clogged enough not to break the siphon and to have the pump slow down a little bit and you will have a flood.
Lower the "T" a little bit to see if you can improve the flow and use a smaller pump on the return. If its flooding out the top of the "T" add an extension so its above the waterline.

A friend of mine tried to make a system like this work for a canister filter and multiple tanks, it ran fine for about 2 months. Then disaster struck, one tank flooded and the other 2 tanks had about 3" of water left in them when he got home. Good thing it was in the garage and no fish were lost.

 

[JoelB]

You can always try a glass/acrylic weir around your tank drain hole? It will be less obvious than a standpipe and will set your water level without drama.

 

[justin guest]

In my opinion you have one of two problems.

First possibility is your 3/4 drain hole in the tank is too small to let enough water through an overflow system running at tank surface level regardless of piping diameter outside the tank, and therfore a siphon effect is necessary to keep the sump filled with enough water for the pump.

Second possibility is that you have used a piping diameter for your overflow that is large enough to supply the sump pump with enough water when a siphon effect occurs, but too small a diameter to allow the necessary amount of water to flow as an overflow system.

j<><

 

[mikeandannie]

I suggest tone down the pump, 1- 3/4 inch drain = 350gph, also I suggest like JoelB suggested a intank box overflow. you can only filter/pump what your overflow can handle, If you can not its a flood waiting to happen. There is alot of options out there for intank boxes, also if you are good with plexi-glas and silicone you could come up with a good DIY one. I just threw this in here to show how much less pvc you would have to worry about. hope I helped...

 

[nfored]

I have thought about the airline clogging as seen in post #7.

Lowering the T create more problems then it solves, lowering the T only gave me unnoticeable flow increase but gave me more water to deal with in a power outage. as seen in post #4

luckily this is in the basement exactly 2 feet from the main drain, so if disaster strikes it wont be so bad, for me, but I do worry about the fish.

But for some reason after reading this I got a great Idea.

Buy this
http://www.petsmart.com/product/ind...04-095F-DD11-98CA-001422107090&utm_source=cse

put in a T close to the bottom of the airline where the airline connects to the cap, and hook this up there.

This way If the the airline clogs everything keeps working like it should until the power fails as the airline is normally seal "clogged with water". when the power fails this air pump kicks on and pumps air into the drain breaking the siphon.

What do you think?


http://www.monsterfishkeepers.com/forums/showpost.php?p=1994888&postcount=7

 

[JoelB]

Lowering the T will do nothing but change your water level. During normal use there will be no difference.

Using half siphon half not is unreliable and unpredictable the way you're describing it as there is no regulation of the flow.

If you're going to use the siphon effect, you should go all the way or not at all. You are heading for a flooding disaster.

If you use the siphon method, you need a new way to set the water level (like a standpipe or a weir). Otherwise, if you are creative you could produce an external weir using your current style of plumbing.


I may have missed your answer from before, does the water in the pipes actually go over the top of the T in normal use without the siphon effect?

 

[WalterMelon]

You could just cap the drain in the bottom of the tank and drill a new one in the side near the top, or put on a siphon overflow box... A hole in the bottom of the tank with no standpipe or internal overflow box.... just seems a little risky to me.

 

[JoelB]

I may have missed your answer from before, does the water in the pipes actually go over the top of the T in normal use without the siphon effect?

You answered this in your original post, sorry, my bad.


This might stop the flooding. Not because of the box but because of the big drain. The box obviously isn't essential. You may simply find some pipe size changers (funnels) to do the same thing.

The fact that the T floods.... suggests that the tank will push it's water level up the pipe with no problem but the drain is too small.