Aqualifter won't stop siphoning

[accel]

So yesterday I had been testing the CPR CS90 overflow HOB and aqua lifter on a separate tank to see how it can handle various cases when the power dies.

Scenario 1: Return pump dies
Problem: A back siphon hapoens where the return line is sucking down water from the main display
Solution: I found I needed to add two 1/8 holes near the water line on the return hose to break the siphon. Tested and it worked

Scenario 2: Aqualifter dies. Return pump dies
Problem: No problem at all. The back siphon is resolved as well

Scenario 3: Aqualifter power dies. Return pump lives.
Problem: No problem. The overflow still works.

Scenario 4: Return pump dies. Aqualifter lives. Same as scenario 1 except I want to list a different issue here
Problem: AquaLifter keeps siphoning water.

I'd been Googling and can't find a good answer. My keywords might be wrong. I want the Aqualifter to stop sucking water when return pump dies. Or at least stop at a certain point. The annoying part is it makes loud sounds when it tries to suck water that it can't get anymore from the main tank.

Going with the lifereefer HOB and drilling tanks are no longer an option.

[mcgyvr]

The aqualifter will allow a siphon to form anytime the input is higher than the output..

Its not a real problem in your typical HOB overflow situation.. and I would accept it..
Just think of it as an audible alert letting you know your return pump dies..

If you wanted to prevent that there are a few ways.. None are really cheap/easy..
1-Monitor energy consumption of return pump circuit and disable aqualifter if you detect its off..
2-Install a float switch/relay to turn off aqualifter when the water level in the sump rises over a specific amount (which will happen when return pump is off).. This may cause other problems and would prevent the aqualifter from being on at startup when it can be really needed so this really isn't a good idea at all..

[ClownNut]

it will do what it suppose to do, sucking water from that overflow "vent" as long as there is power to it. you can redirect it flow back into the display tank instead of into the back of the overflow box. or do what mcgyvr suggested have a flow switch in the sump to turn it off when the water level hits a specific height.

[accel]

Thanks mcgyvr and clownnut. It's good to know this is normal.

I can certainly create some custom float/relay switch since I'd been dabbling a lot with IoT for the past year and a programmer here as well. I'll see if it's even practical.

As you've mentioned the audible alert is a good way to know something is wrong.

[mcgyvr]

All pumps that do not have a positive block of the flow path can suffer from siphon issues..
Centrifugal pumps (normal aquarium pumps), diaphragm pumps (aqualifter) ,etc.. will show that problem..

Peristaltic pumps will not as the rollers block flow of the path completely at all times..
So you can just change to a peristaltic pump too if you want..

[d0ughb0y]

Originally Posted by mcgyvr

All pumps that do not have a positive block of the flow path can suffer from siphon issues..
Centrifugal pumps (normal aquarium pumps), diaphragm pumps (aqualifter) ,etc.. will show that problem..

Peristaltic pumps will not as the rollers block flow of the path completely at all times..
So you can just change to a peristaltic pump too if you want..

the brs doser peristaltic pump uses only 2 rollers and as such, there is possibility that rollers can stop at a position without pinching the hose and thus creating a siphon.

[Member No. 1]

Originally Posted by d0ughb0y

the brs doser peristaltic pump uses only 2 rollers and as such, there is possibility that rollers can stop at a position without pinching the hose and thus creating a siphon.

In theory, as long as the inside dia. of the housing is greater than 180*, then no matter where it stops, the tube will be pinched.

The DOS uses 2 rollers, I have it mounted below the water level, never had a siphon problem.

On the other hand, my Litermeter III is a 3 roller design which is much better. And on the plus side, the Littermeter uses a check valve in the input.

[mcgyvr]

Originally Posted by d0ughb0y

the brs doser peristaltic pump uses only 2 rollers and as such, there is possibility that rollers can stop at a position without pinching the hose and thus creating a siphon.

It shouldn't.. Its surrounding race design is such that its more than a half circle and as such shouldn't ever allow a siphon..
If it does its faulty as that would prevent proper operation of the whole thing

[accel]

Just a follow up. Not sure if this deserves a new thread.

Since the CS90 has a big space, is it possible for me to add a filter sock or a poly-filter pad there for extra filtration. I know I can put those in the sump, but would I have problems if I maximize that space on the HOB anyway?

I was kinda thinking it can be a small breeder area as well or something like that.

[mcgyvr]

I would never recommend putting that stuff in there.. Just increases its potential for failure due to lack of maintenance/clogging..
Do not do that..

[accel]

Thanks mcgyvr

[d0ughb0y]

Originally Posted by mcgyvr

It shouldn't.. Its surrounding race design is such that its more than a half circle and as such shouldn't ever allow a siphon..
If it does its faulty as that would prevent proper operation of the whole thing

I just came across a thread in the "other" site where some people experienced siphoning on peristaltic pumps if the dosing container is higher (like placed on shelf above sump) than the output. I think regardless if it can happen or not, best is to make sure output is always higher than the dosing container liquid level.

[Member No. 1]

Would be a little difficult in my case, tank/sump on ground floor, AWC drains to washer waste pipe in basement.
I did however create a siphon break above the sump.
But with the new tank upgrade, I will be installing a check value inline on the waste line leading to the basement.

[mcgyvr]

Originally Posted by d0ughb0y

I just came across a thread in the "other" site where some people experienced siphoning on peristaltic pumps if the dosing container is higher (like placed on shelf above sump) than the output. I think regardless if it can happen or not, best is to make sure output is always higher than the dosing container liquid level.

If a peristaltic pump is having a siphon issue then its faulty/out of adjustment.. Worn tubing/improper roller adjustment,etc...
But yes.. not creating a situation where a siphon can form is a good failsafe..

[d0ughb0y]

I was surprised to see more than one person experiencing the issue. it may be worn parts, as I think it happened after about a year of use. its for dosing pump RB sells.

btw, check valve will prevent back siphon, but not forward siphon. The siphon break will stop forward siphon.

[Member No. 1]

Originally Posted by d0ughb0y

SNIP--->

btw, check valve will prevent back siphon, but not forward siphon. The siphon break will stop forward siphon.

True, but the 1/4" inline check valve has some sort of spring to keep it closed. The force to open is greater than the siphon draw, to a certain extent.
The vacuum created by the pump is more than enough to overcome the spring and open the valve.

[d0ughb0y]

siphon suction may be stronger for elevation difference between first floor and basement. test to make sure. I would not underestimate the power of siphon.

[Member No. 1]

Originally Posted by d0ughb0y

siphon suction may be stronger for elevation difference between first floor and basement. test to make sure. I would not underestimate the power of siphon.

That's my plan!