Backwash queston

[TomAtlanta]

In pool school, under maintenance of sand filters, it says:

After turning off the pump, move the lever to the "BACKWASH" position and restart the pump. Most multis have a view glass so that you can see the debris coming out of the filter, other filters will have a section of transparent pipe on the backwash line. The water will run clear for a moment, then get dirty, and finally run clear again. When the water in the glass is ~ clear, turn off the pump. If you have a multiport valve with a "RINSE" setting, switch the multiport to "RINSE", otherwise switch to "FILTER", and run the pump for about 15 seconds. Repeat the backwash cycle.

What is the purpose of doing the backwash cycle twice? If you want to get it extra clean why not just run backwash a little longer after the water is clear? What is gained by doing
backwash/rinse/backwash/rinse ? What does that extra rinse do?

My understanding is that rinse is just removing water from the filter without the water first going through the sand, while backwash runs water backwards through the sand and then removes it.

What am I missing?

 

[JasonLion]

Doing the entire cycle twice helps dislodge debris that has gotten stuck somewhere. The repeated reversals of direction tend to shake things loose. Personally I don't consider it essential on a sand filter, but it can make a large difference with a DE filter.

Rinse removes dirty water from the multi-port valve and the plumbing lines between the filter and the multi-port, preventing any debris in that water from going back into the pool.

 

[TomAtlanta]

Thanks for the info. Do you know of anywhere online that has a good diagram of water flow in sand filter and multi-port valve? I may be confused about exactly what the different cycles do, and one picture is worth a thousand words.

 

[jblizzle]

Picture may confuse things ... although I have not seen one. Here are the different modes:

Filter = Water enters top of filter and passes down through the sand returning to pool
Backwash = Water enters through laterals at bottom of filter and passes up through the sand and carry dirt out to waste pipe
Clean/Rinse = Water enters top of filter and passes down through the sand and out to waste pipe
Waste = Water bypasses filter and heads out waste pipe.
Recirculate = Water bypasses filter and returns to pool

 

[JamesW]

http://www.azpoolcare.biz/filters.php

 

[TomAtlanta]

Thanks for the description and the picture. My filter has all the pipes coming out of the top. It is a hayward valve. I guess the principles are exactly the same.

 

[TomAtlanta]

I just vacuumed the pool. My vacuum fits into the top of the skimmer. When I finished I cleaned the skimmer basket, then cleaned the pump strainer basket. The pump and filter are down hill from the pool and usually when I clean the pump strainer basket water flows out, but this time it didn't. I started the pump and the pressure was only 5 (normally 13) and there was not much water coming through the pipe. I turned the pump off, then on again. Same thing. I waited a few minutes, turned the pump on again and got normal flow. What could have caused this? Could the pipe from the pool have gotten clogged while vacuuming?

When vacuuming I had the filter set on the normal filter setting, then when I finished and got the flow back to normal I did backwash and rinse. Is that the best way to do it?

One other thing. When I first tried to move the valvue to backwash it was stuck and would not move. The pump was off. Later I was able to move it.

When I first got the pump working at normal pressure, I went back to the pool and it was blowing out lots of air from the returns. After backwash and rinse, no air.

 

[TomAtlanta]

Someone mentioned in another thread that backwashing too much can be a problem. How much is too much, and what problem does it cause?

I always get a lot of air in the filter when I vacuum. There is no air release valve. Backwashing removes the air, so I always backwash after I vacuum. Is this going to cause me a problem?

 

[jblizzle]

I can not think of a real problem that would develop from backwashing.

Obviously you are replacing more water so some levels may need to be watched more closely.

Posted with Tapatalk ... sorry if I sound short ... hate typing on phone