Return Pump Check Valve Problem

[jagillham]

Problem!

So I've put my return outlet through the base of the tank, sits only about 10cm from the base of the tank inside.

I've a 22mm non-return valve on the pipe to prevent the tank draining out in the event of return pump failure. Tried it today, and seems to have gunked up / not worked. Any ideas on saving this idea?

Currently sitting one powercut from 500l of water on the floor and lots of dead fish!

 

[foxfish]

Do you know how the valve works, there are a few different types, is it a valve that is supplied it’s the tank?
Every non return valve I have used, effects flow quite a lot, some spring powered ones are extreamly restrictive while the rubber flap models are better but still restrictive.
If it is a ball style then they are the best but all the styles I have come across need regular maintaining or at least checking and cleaning.
It only takes a tiny bit of hard dirt to stop a non return valve from fully closing.
Depending on the situation, I would normally place isolating valves either side of a no return valve to aid maintainace but they also cause even more flow restriction.

 

[jagillham]

@foxfish - Not sure exactly what type it is, but appears to just be a 22mm single plumbing one from B&Q or similar. Not quite how to describe how it is inside, a plug on a spring which sits in line. Not obvious obstruction, just has that slime in it pipes tend to have.

I’m thinking of putting a new double one in whilst I find alternative solution.

 

[zozo]

That looks like a ball type mainly used (made for) in the clean water supply line.. Beter look in the pond shops for a PVC version a bit more bulky build. But designed for easier maintenance and cleaning..

Or the transparent design..

http://www.koi-zone.co.uk/Pond-Construction/Non-Return-Valves-sc-1246.html
.

 

[jagillham]

Upon closer inspection, valve was not closing due to 3 baby MTS snail shells being caught in it. Bit scary that and and power trip would be enough to flood the room!

Replaced the valve with a double check valve. Does not solve the issue, but does add some redundancy into the equation. What I need do do is pre filter the water coming into the sump to prevent this issue.

 

[foxfish]

I can’t think of any easy way around this, short of changing the whole concept!
Obviously you could extend the return pipe up to near the tank surface but that would require as massive rescape in order to hide the pipe, or you could block off the existing return and just go over the top like the average tank does.
Unless you can regularly check the check valve there will always be the threat of the valve failing but how often would you have to clean the valve to feel safe?
Where I live, I would say we get around one power cut a year.

 

[ian_m]

You can't really ever put a non return valve in dirty water supplies, they will always find something to jam them eg snails, plants, limescale etc. Industrially you would use a motorised (or spring loaded) valve to prevent dirty water back flow in dirty water.

You need to explain more why you require a non return valve in the sump feed, not really a done thing.

Most people have sumps with a "power fail to safe setup", rather than power fail to flood, without the use of non return valves.

You appear to have a sump system that can fail to unsafe.

 

[jagillham]

Cheers @foxfish & @ian_m

The “smart” idea was to have the return flow low across the front to solve the lack of flow issue. Older pictures below, but you get the idea.

The sump will overflow into the drain once set up properly, which solves the flood the the room issues. This is also how I do the 50% weekly water changes.

I did similar on my last tank, but with the return higher, so drain out was not such an issue.