Comments for No Water Flow Through Glass Sight Gauge On My Filter System

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Sep 16, 2014
Leakage into Pump Chamber
by: Nick

Thanks for this reply Robert. By pump chamber I mean the whole works including pump, chlorinator and spheroid sand filter/pipework is in a plastic container unit/chamber which recently has been filling with water although all the unions ie pump and filter/backwash mechanism pipework seem dry. No rain so the only possible leakage point TO ME is from somewhere on the sand filter which is obscured from view.

Thanks for the follow up but I'm unsure to what the question means. When the pump motor turns off the water should stay in the plumbing, filter, and pump pot. If there's a leak somewhere you'll have a noticeable and audible loss of water in the filter or pump pot. This can happen with a leak from either the suction or return side. There may also be a gurgling noise as the water empties from the filter and/or pump.

This is why I'm a bit confused when it's said the chamber fills with water. The system is already filled with water and should stay filled when the system turns off. The water level shouldn't decrease then increase.

So let's start from the beginning. You turn the system on and it filters properly, everything is alright. The system is full of water and there's no cavitation in the pump pot. No leaks around the pot lid, unions, and the sand filter doesn't seem to be leaking. You turn the system off. At this point what happens? Does it lose water? Do you have any solar panels or a check valve? This may be the issue.

Sep 21, 2014
Leaking Sand Filter Unit
by: Anonymous

Thanks Robert I have finally found from where the filter unit is leaking. Its from the bottom side entry pipe unit as it enters the filter unit. I have been told that the 8 year old sand has likely become so clogged up that the thick rubber seal on the inside must have broken and the 150mm pipe and seal will need to be replaced - costing 700 Rand and obviously the sand needs replacing. Have you any comment please?

Thanks for the follow up

It sounds like the bulkhead on the filter is leaking or went bad. It's easy to replace, very similar to screwing in a light bulb. If you do get the bulkhead it may have a notch, about 1 inch long in the threads. Be sure that's correctly lined up with the filter opening. Also, some BH washers are very slightly curved. Be sure they're lined up as well. You can't see it looking at it straight on so be sure it's on its side.

#20 silica sand is what many manufacturers recommend but check with the owner's manual for this. Be sure to put the right amount of sand in but also check the freeboard. This is the measurement from the top of the sand to the top of the filter and is very important.

As sand gets wet, is used, and settles the freeboard will increase and reduce the effectiveness of filtration. Simply top the sand off with an inch or two of sand.

Also be sure to check the laterals while the filter is empty. Look for cracks or breaks and replace them if needed. The laterals may become packed with sand so clean them out.

A bulkhead costs around $90, or about 1000 Rand. I did a money exchange on the internet and that' what I came up with.

Remember that I'm open for consultation if needed. I don't have a set amount so I leave it up to the individual.


Apr 11, 2016
Water Flowing Out Of Sight Glass
by: Anonymous

When I back washed my sand filter the water flowed freely out of the sightglass also when I rinsed after backwashing the water flowed freely out of the sightglass is this supposed to happen?😳

Hi. It is uncommon for water to be in the sight glass. Sometimes you'll see a little bit but it's normally reserved for backwashing. When you say flowing out of the sight glass I will assume the actual site glass has a leak.

I depends on the kind of filter you have. Some filters have a built-in glass while other like Hayward can be replaced. Simply turn the pump motor off, unscrew the old one and replace. Also, there could be an o-ring that's easily replaced. A couple of dollars and you're back in business.

Water in the sight glass may also indicate a bad spider gasket which is found in the multiport valve body. Try the easy route first and if that doesn't work you'll need to check the spider gasket and replace if needed.


May 02, 2020
Same issue
by: Anonymous

Morning, my pool is doing the same thing sort of. I have no water in my sandfilter sight glass but have great pressure and water coming out into the pool. Do you think it would be safe to say the mulitiport valve o ring is bad? Or just a bad valve?
Same as other ppl the sight glass fills on backwash and drains away once I put it back to filter.

The sight glass, if you're talking about the little bulb on the side if the filter, is normally used for backwashing purposes. If you don't have any leaks and the filter is perfectly working and getting good pressure from the returns, no reason for any alarms.

Aug 11, 2022
New sand, lots of chemicals, but my pool has turned lime green !
by: bob

Water is passing through the filter and the pump. The only unusual things I notice are that when backwashing (a) dirty green water is visible at the top of the filter for a while, and (b) the sight glass stays completely clear, almost as it it was empty.

There's loads of chlorine, flocculent, and algicide in the pool, but it has turned green. The only change this year from last, other than the 2 points above, is that a friend of mine changed the sand in the filter.

Any ideas what I can do ? At present the pool is being filtered 24h a day... with no improvement in the water. In fact, it may be becoming even greener !!!

Hi Bob

Here's a video I did on clearing up a green pool.
Clear Up Your Green Pool

Give it a watch. It has tons of great info. If you'd like to dig deeper, I have several resources available.


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