Backwashing

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Captain 776

Captain 776

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May 2, 2016
165
Thailand
Hello,

I have had my pool 2 yrs and a few problems and either by myself or with help from the great guys here got them resolved.
For many months now my water is balanced and crystal clear and I have never had an algae problem.
I use a fine mesh stainless screen, a kitchen strainer actually on top of my skimmer basket, it works great to catch many fines, keeps all that very small debris from ever reaching my filter. That allows for less frequent backwashing and altering my chemistry.
I hadn't Back washed my filter in about 6 weeks or so.
I Back washed it a few days ago and the sight glass showed it was very dirty both on the backwash and even got brown for a bit during rinse, but as I was standing there during backwash it looked like dirty water in the filter basket just before the suction inlet to the pump.
i had never seen that before in the 2 yrs of doing this and sure enough it blew fine dust like particles back into the pool.
the next night when the pool was still, I turned on the lights and could see a fair amount of what looked like dust flowing past the lights.
In 2 days it does not appear the filter is clearing this up.
It just dawned on me to remove that fine screen from on top of the skimmer basket because it may be preventing the fines from getting into the filter, I am now letting it run 24 hrs and check it tomorrow night and see if I see any improvement.
I had a similar problem a yr ago because the builder got so much sediment and muck in my main drain line and it had solidified during construction, once I figured that out, I got the line clean, then used Flocculant and it was amazing how well that worked, since flocking my water is so clear, it was like looking through air, now I have a mess again.
Not sure my filter is going to catch all of what is suspended in the water now.
I will be near the pool store tomorrow anyway and I plan to get another bottle of Flocculant. If it still looks the same tomorrow night after a 24 hr run, I plan to flock it again.

One thing, when I put the multiport handle in the backwash position, it didn't feel right, felt like the pointer didn't sit all the way down in the slot, but I am not sure of this though.

From now on, I plan to close the return valve when I backwash but leave the skimmer and main drain valves open.
Do any of you typically close the return valve when backwashing? Should I have been doing that since Day 1 anyway?

During the first backwash cycle, I definitely noticed the water in the filter before the pump looked like dust suspended in the water, to me, the only way that could have happened was if the multiport handle was not fully engaged.
I did change my spider gasket about 10 months ago and had no problem with it, it was an easy job, I cleaned it and lubricated the new gasket well and it has been working fine and my water sparkling up until I Back washed 4 or 5 days ago now.

Any input / ideas appreciated of course and please answer........do you pros close the return valve during Backwash?

Thanks

bruce
 
I never close returns when backwashing if the multiport valve on the filter is working, no water should be going to pool when in backwash or the rinse modes. Do you shut off your pump between switching positions on your multiport valve? You would want to make sure pump is and switch valve quickly between positions.
 
When you say this: " but as I was standing there during backwash it looked like dirty water in the filter basket just before the suction inlet to the pump."


This is before the filter and simply the water coming from the pool... water is flowing from this basket towards your filter, so none of the dirt being cleared from your filter during backwash could possibly be making it backwards towards the suction strainer basket on your pump.

Is it possible that you have a variable speed pump, and when switching to do the backwash it was in a priming mode, which caused a significant increase in flow that sucked more dirt from the screen in your skimmer?

If I'm understanding your scenario and your plumbing correctly, any dirt that you might see in the pump suction strainer would have to be coming directly from your skimmer and/or main drains depending on piping and valving.

One thing that may have caused dirt to re-enter the pool is too short of a backwash, and rinse cycles... I don't know what others recommend for time, but if you don't let it run long enough, particularly on the rinse, you may pump some of the dislodged dirt back into the pool. I would say let it backwash and rinse for at least one full minute after the sight glass looks completely clear.

You shouldn't have to close return valves while backwashing.
 
Bruce, like the others above, if your multiport valve is working properly, there should be no water flowing to the pool during backwash. That's one indication that something may need attention. As for the particles you are seeing and the filter's ability to keep your water clear ... a sand filter should work just fine. I would be cautious about the use of Floc as it can tend to mess-up your filtration system if the floc is allowed to get in there. In fact, if your multiport is failing in some way to keep a good seal, then some floc (used in the past) may have already gotten to the sand. As noted above, a thorough rinse is especially important as well.

Before you consider a floc, I would recommend two things: 1 - Re-inspect your multiport valve/gasket. Based on your descriptions of water flowing back to the pool and the valve not settling-in firmly into place, something's not right. You need a good seal at the multiport. 2 - Consider a thorough deep clean of your sand filter as noted on the TFP Deep Cleaning a Sand Filter page. As long as the quality of the sand has not been compromised by previous pool store products, a deep clean may help enhance your system's filtering ability. Also make sure to allow adequate time for rinsing and let us know if you see any changes or improvement. Have a nice day.
 
After letting it run 24 hrs it looks quite a bit clearer, maybe a few more long cycles can recapture what I was seeing when I turned on the lights.
I withdraw the statement about seeing the dusty water in the strainer basket before pump, that would be impossible with the pump on and it would mean it was coming in from the pool but my pool was crystal clear before I backeashed.
I do not have a variable speed motor.
My filter material is glass not sand.
I only used Floc one time and was careful to vac it all to waste over 3 days to be sure I got it all out and my pool was so clear after the floc.
I got in the pool with a mask and snorkel so I could see I was getting all of it to waste.
I agree with the advice of floc as last resort, it was a chore to get it all out and then re-establish balanced chemistry.

It looks much better than this morning than I anticipated.
let me see what it looks like after another long run cycle.

thanks
 
The first pic is a close up of the chunk of debris that was in my filter basket before the pump today.
The second picture shows how big this was, about 9 cm
The third pic is a bag of debris I have removed from the main drain line over the last 2 yrs and it doesn't represent all the debris I have removed from it as I didn't save every piece.
I believe this is the root cause of the fines I am seeing in the pool now when it is still at night and I turn on the pool lights, it looks like a dust storm going by the light.
The pressure from the pump is wearing away at these pieces and I see the suspended fines.
I thought I had this resolved a few months ago when I removed many pieces, then Flocc'd the pool and after that it was so clear, it was like looking through air.
but now I am having this problem again. I incorrectly thought I had blown dirt back into the pool.
These pieces appear to be construction dirt, dust, mud, and maybe grout from when they were washing out during grouting of the riles without protecting the main drain piping.
The pieces are firm but you can crumble them with your fingers.
I will see how it looks tonight when it is still and I turn on the lights, if I still see a lot of what looks like dust going by the light, I will Floc the pool again, it took it all out when I did it before.

i was not here when the piping was done, but surely they did not cap off the main drain line.

If you are building now or in the future, REQUIRE the builder keep ALL pipe ends capped during construction, especially the main drain because that is the lowest and easiest to get filled up with mud and debris.

stay tuned

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Wow, those are huge pieces getting through to the pump strainer! It sounds like you've identified the problem, that's great.

The particles that come off those chunks will filter out using your filter, but it may take some time. I think you can do it just with the filter and without having to bother with floc. It's good that water is flowing from your main drain and not entirely plugged! It's amazing the material can find it's way around corners and through valves. Sorry to hear that they were sloppy during construction. I'm sure you remove those from the pump strainer as soon as you see them lest they tumble around and make more dust.

Be sure to let your filter get dirty enough to filter at its best. Backwashing can be delayed until filter pressure rises 25% above clean pressure, to extend the time that the filter is a bit dirty and filtering at its best. You can also add some DE to the filter which might help you clear the dust faster, but certainly not essential at this stage.
Pool School - Add DE to a Sand Filter
 
I just checked now that it is dark and the water is still, looks awful, significantly worse, not better at all.

The first time I used Floc, there was a lot of brown dust bunnies on the bottom of pool the next day, but this morning, there was almost nothing.
The first time I applied with a small garden sprayer to get an even coverage, but I no longer have that small one.
I have a bigger one now, so when I dumped the bottle of Floc in yesterday, I added water, maybe that is why it did next to nothing.

Do you add water to Floc to spray it, the bottle mentions nothing about that just says 10 ML/M3. Should I have used the Floc full strength?

It is such a mess now, I don't think my filter will ever remove it all.
My pool and filter is 2 yrs old and has always had Glass Media.
I was going to change to Zeolite when I had this problem last year but after Floc, it was so clear, I didn't bother.

For the experts and those that know:
What are your views of Zeolite vs Glass

LQQk close to the light in this picture, you can see the dust storm it looks like dust in the water but I have no idea what it is or why my water turned went bad almost overnight.

Frustrated~!!
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Lots of issues here, Bruce, that makes for a very incomplete picture.

You have no test results. Everything we do should be based from current test results.........everyone is just guessing.

Next, from my personal experience, all bets are off once you choose to use floc. Flocullants are quite often the source of even greater trouble and that seems to be the case with your pool.

Skimming this thread, I see no mention of using the rinse cycle.

Are you doing that?

Can you post valid test results today?

Do you have a picture of the pool water now?
 

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It is 11:40 PM here now.
I will do a full range of tests in the morning.
when I backwash I always rinse
During backwash, I let it run a while then stop for 30 seconds, then restart to mix it up as best I can.
I do the same on Rinse.
The sightglass got dirty during the rinse cycle also and I don't recall that happening before
The pool has been sparkling clear for a several months and this new problem was first noticed when I Back washed 2 days ago.
I had not Back washed in 6-8 weeks
The sightglass was the dirtiest I have ever seen it in the 2 yrs I had this pool.
I let the Backwash run until sightglass was clear, I pumped about 2 inches of water out of the pool during Backwash and Rinse.
I can't be sure because it was still sparkling before the Backwash because I wasn't anticipating a problem but I believe it was clear
I will heed your advice and not use Floc again
I was going to let the pump run all night but I just checked it now and it looks worse now than it did at 6 pm, 6 hrs ago so I shut it off.

I will post a full set of number in the morning and pictures after the water has been still for the next 6 hrs.

thanks

Bruce
 
I suspect that part of the problem is that the multiport is not seating correctly. I would open the multiport, check the gasket, take out the diverter, lube the diverter stem o-rings and then make sure that the multiport is reinstalled in the proper position.
Can you post a picture of the filter and the multiport?
 
9 am Sunday Jan 22:

Salt - 2710
FC - 15
CC - -0
PH - 7.8
TA -70
CH - 170
CYA - less than 30

Are my CSI values in this Pool Math OK ?

It is calling for 28.5 pounds of Calcium Chloride, I am hesitant to add that much.

here is the Pool Math Results for this morning tests
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5 am this morning, you can see how much cloudiness in front of light
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I did the PH and Chorine both ways, with Colorimeter and with Taylor 100
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PH with Taylor 100
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James asked about pics of Filter and Multiport
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Multiport Valve. I replaced the spider gasket about 6 months ago and lubricated it well and reassembled. No problem, easy job
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Pump and Filter
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I look forward to your comments what I should do to remedy my cloudy water issue.
 
The plumbing looks correct. Maybe check the gasket again. Maybe lube up the diverter stem o-ring.

One thing, when I put the multiport handle in the backwash position, it didn't feel right, felt like the pointer didn't sit all the way down in the slot, but I am not sure of this though.
Click to expand...
This concerns me a little. Maybe the gasket did not seat properly.
 
This is an outdoor pool....correct?
Tell us about your pressure.
What is normal psi?
Did it rise when pool was dirty?
Did it return to normal after backwash?
How often do you backwash and why?

I have some other questions but let's get to the above first.
 
Here's my theory, FWIW. The problem arose suddenly after many months trouble free. It arose during a backwash, when the pump is flowing more water than normal. Brown water in the pump strainer came from the pool somehow, yet none had been there before. Also, massive chunks of construction debris arrived in the pump strainer. One in particular looks like a geode of dirt, plaster, and grout from all the tiling.

So my theory is that this crud has been there in the main drain since construction. It was probably eroding very slowly, but finally let go when flow was high enough to peel it away. Flipping those chunks released the dirt that would have been under the grout. If I'm right, it's great luck that the drain is finally flowing.

This release would put a ton of fine dust and dirt in the pool, and it will take a week or two to get it filtered. Keeping the water well stirred up and "looking awful" and the pump running 24/7 will get rid of it, in my humble opinion :) High FC during this period is great insurance against everything coming in with the dirt. I would even draw all water from the main drain, on waste, every day for a minute or two just to keep washing it out and displace as much of it as possible.

As a follow-up to a couple of questions, it's normal to see dirty water during the rinse. Make sure the rinse is long enough. Mine takes 2 minutes, same as my backwash.

Re: glass vs. sand... some glass for filtration is better than others, and this is the main reason not to use glass media. If you change it, just get conventional pool filter sand of the correct TFPC specification. But personally, I don't think you need to, because you were getting good results before.

These guys are way better experts than me, so be sure to answer all the questions and you'll be right back into sparkly pool before you know it.
 
Hi Dave,

I have answered your questions below.

duraleigh said:
This is an outdoor pool....correct?
Tell us about your pressure.
What is normal psi?
Did it rise when pool was dirty?
Did it return to normal after backwash?
How often do you backwash and why?

I have some other questions but let's get to the above first.
Click to expand...

Yes this pool is outdoors.

My normal pressure is 19-21 PSI

I didn't look at the pressure before the Backwash when I noticed the problem. I have fine stainless Steel screen on top of my skimmer basket that catches all the very small debris that would normally go through the openings on the skimmer basket. Between that strainer on top of skimmer basket and the Ultra Fine basket in my Dolphin S-100 robot vacuum very little amount of fine particles are getting to my main filter. Putting the screen on top of the skimmer basket it just my idea. It is really a kitchen strainer that fits exactly on top of my basket after I ground the handle off of it.
I put the robot in the pool 4 or 5 times a week. I am up at 5 am anyway every day, I put in, remove it after it's 2 hr cycle, clean it, then let the pool do its regular daily cycle and all was well.

NOTE: It is cool now here at night and in the morning, 55-60 at night and 80 by 10 am.
I was running 7 hrs before we started cooling off, but when I was testing, my FC was usually 7-10. I cut my run time to 5 hrs a day and had been on 5 hrs a day for 3 months before I noticed this newest problem.
I did the FC test this morning with the Taylor kit and 15. Then I also did it with the color tube method and posted that pic, you can see it is off the scale, bright yellow.
2 nights ago, when I was looking at the cloudy water with the lights on, I could see small bugs swimming around the lights underwater, so I dumped in 1 gallon of liquid bleach and let the pool circulate for an hour. That may be why my FC is 15 today.
I am trying to give you all all the info I can to better help you......help me.


I have my SWG ....OFF until my FC level comes back down.

I didn't look to see if the pressure was high before Backwashing so I can't say it returned to normal. When I stick my head in the door of the Pumproom, which is frequently just to make sure all is well, I am looking at the number on the SWG Control Panel, make sure nothing is leaking or dripping, seeing the basket before pump needs to be cleaned, and when doing those things, I always look at the gage, it always seems to be 19-21. I don't recall ever seeing it higher or lower.

In the beginning of having this pool, I was backwashing every week or 2 but noticing the sight glass rarely if ever would show dirty water during Backwash. Then I had the idea to put the strainer on top of the skimmer basket so less small debris gets into main filter and I was Backwashing less just from that point.
then I discovered this site and from reading many threads and topics here, I think I was Backwashing way too often.
For the last Backwash when I noticed this problem, like I said above, it was most likely 6-8 weeks since I had Backwashed.

Thanks

Bruce
 
1. Let a pressure rise be the indicator to backwash. Wait until your psi rises 25% from the normal of 19-21 (about 25 psi) and then back wash. Your pool looks very clean so it may be a Lo-o-o-ng time before you backwash......that's OK.

2. I like needsajet post and his theory of the origin of the "geodes". Where do you think they came from?

3. How do you vacuum your pool?

4. Your CYA is too low......it should be around 50 ppm

5. Your pH looks more like 8.0 to me. I would lower it to 7.4 - 7.6

6. Have you thoroughly read "The ABC's of Pool Water Chemistry" up in Pool School?

7. You have done a very nice job on your pool to this point. I would encourage you to keep asking questions and learning.


PS -
Putting the screen on top of the skimmer basket it just my idea.
Click to expand...
Make sure you are not restricting the flow. Have someone watch psi as you take on and take off the skimmer basket. If the psi drops by 3 lbs or more, I would keep it off.......it may not drop the psi at all but it's a good idea to check it

Each time you check on your equipment, check that pressure gauge. It is an essential part of your system and will tell you if anything is amiss with your circulatory system.
 
Hi Dave,

Thanks for the info, I value your advice and the advice and input from others.

OK, I will keep an eye on the pressure and let tell me when to Backwash.

To vacuum, I use a robot, Dolphin S-100 with Ultra Fine basket. I have had it 9 months now and it does a very good job. I note where something may be on the bottom and then check after a cycle and I have yet to find where it missed something. I have stairs at both ends that the robot can't negotiate. I sweep them a few times a week to move and dirt that may have accumulated on them and every few weeks I hook up the hand vacuum and vacuum the steps.

Yesterday I added the CYA. I dissolve it in a bucket first, mix it with electric drill and mixer until it is all dissolved. I will do another full set of tests today. I also added 15 pounds of Calcium Chloride yesterday from what I had on hand. Pool Math calls for 28 pounds so I put in half. Today, I will also add 100 pounds of salt.

I absolutely agree the geodes are there from poor construction practice of leaving the main drain piping open during construction. Unfortunately, my pool was built by a guy who decided to become a builder at age 60, he sub'D out just about everything on the first house including the pool, then he thought, that looked easy so in house 2 and 3 he used local inexperienced labor at 10.00 dollars a day, yes, 10.00 a day, going rate here in Thailand. Even house 1 had major problems when all the piping broke, because they never compacted anything. House 2 and 3 also have pool problems.
I was house number 4.
My pool was losing 2" every night, we tried everything to find the leak, we broke out my tile and concrete 4 feet sq in 2 locations, and when we broke thru the concrete, the dirt was 3-5 inches below it from where it settled due to no compaction.
Last thing we Che led was the lighting conduits......BINGO, that was the leak. He actually said to me, hmmmmm I thought this connection would be above the water line so I didn't glue it. We are talking 1/2" PVC, when the ground settled, it easily pulled the pipe out of the socket.
Hopefully I don't have future problems from this.
House number 5 is across the street from me, when they poured the concrete, the form blew out, what a mess.
That house has been sitting there about 80% complete and the pool and hot tub which is part of the pool is full from rain water over the last 2 years.
None of the finish plumbing is done, you can imagine what that looks like with 2 years of untreated water, dirt, debris, leaves and YES.......the main drain is an open end.
He stopped building and now works for a pool company here.
He starts every sentence with " Before I became a pool expert" all I can do not to bust out laughing.

I will recheck my PH and do another full set of tests today.

I have not read the ABC of water chemistry but will today. I am retired and have plenty of time.

Also today, I will check to see if pressure drop with screen on skimmer basket.

thanks a lot for your input and advice, greatly appreciated

Bruce
 

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