If I looked at the sand in the filter, what should I see?

Bought the house w/pool April this year and have slowly been rebuilding things to make them work better. It's an IG 15,000 gallon plaster with a sand filter, probably at least 10 years old.

Not knowing how the pool has been managed in the past, I'm curious what I would find if I opened the top of the sand filter and looked in. It -seems- to be working okay, but I never see anything in the backflush glass thingy. If I opened the top and looked at the sand, what am I looking for, good or bad?

Thanks,

TW

TW, good would be clean fluffy sand. Bad would be black - grey - green film on the top, or visible channels in the sand. However worst would be ... no sand! ;) If you decide to pop it open, stick a finger in there and see if it resists some gentle pressure, you can't always tell by sight how the sand is holding up. Should you open it, let us know what you find.

if i can add to this one a bit..and all the advice is good so far..if the sand is hard, it's not going to filter anything ..or it may be partially hard..but to the point you don't want to go poking a stick in there as you could wreck the vanes inside..but you should be able to easily poke a finger around our 2 fingers and run sand between your fingers anywhere you can reach in the filter if it's good. i believe sand in filters is supposed to be good about 5 years..that maybe rated based on year round use as my sand is at least 7 years old and was still completely "sandy" consistency at the end of last season.

If it aint broke - don't fix it !

I think I'd wait til the end of the season - you may damage an o ring or a gasket. It's easier to look for parts when you don't need them right away.

When you say you dont see anything in the glass - you do see water in there when backwashing ?

Heh, too late.

I opened it up and there was about a half inch of grey fluffy gunk on top of the sand. I scooped out as much of that as I could. Then I dug around in the sand and determined that it was compacted, mostly against the sides and into the tank about 4-5 inches. So I used my hand to uncompact it, then backwashed. Then opened it again and stirred it some more, then backwashed. The pool has to refill now before I might backwash it again before setting it to filter.

I am SO glad I looked at the spider gasket in the multi-port valve a few days ago. It was a gooey mess and had to be replaced. Earlier in the year when I did a complete draindown, I wondered why so much water kept coming back into the pool through the return nozzles, even though it was set to pump to waste. Had I not replaced the spider gasket, a lot of that grey gunk would have gone into the pool today. :eek:

EDIT: The glass has always been clear water, until today's cleaning.

EDIT2: Opened it a third time, stirred the sand and backwashed. Pretty sure I'll still get a cloud of grey water when it's set to filter, so I'll do that later tonight. When nobody is looking. :cool:

Very interesting. What are your thoughts are on why it was compacted?

It seems to me regular backwashing should prevent that. Do you think the "grey junk" could have been from not backwashing frequently enough? Have you owned the filter since it was new?

Oops, just reread your first post. I wonder if the old owner thought backwashing was something he and the wife did in the shower?:D

Why was it compacted? Dunno, maybe that's just what it does eventually? Probably was never properly backwashed in its early years.

I went ahead and turned it to filter, no grey cloud into the pool, so that's good.

Before I replaced the spider gasket the system ran at about 12psi, because it was leaking water around the gasket. With the new gasket but before cleaning the sand, it jumped up to 18psi. Now with the sand cleaned it's running at 15psi.

TW

Been running it 24/7 the last three days as I do the alkalinity adjustment thang. Stop and backwash each day for a minute or so, get a short burst of grey water each time, so that seems to be working better.

One other thing that struck me about the compacted sand - Since the spider gasket was blown the path of least resistance during a backwash might have been to bypass the filter, so even when set to backwash there was little actual effect.

TW

I believe you got it right there with the path of least resistance - it just went to bypass.
WRT the sand compacting, I believe this happens because many people don't know better or ignore recommendations, however, most pool owners i know are adding all their chemicals through the skimmer since it is teh most "convenient" location.
Now, if you add your bleach that way, it likey will not do anything to your sand, however, floculant could easily clump your sand particles since it's designed to clump fine solids. Other chemicals may also have similar effects, algaecide comes to mind (really, why bother mixing it in a bucket first, isn't blowing it out the return pretty much the same thing?).
If sand can last 5 years+ without compacting and solidifying under noraml use, what makes 7 or 10 or 20 years so different, it has to do something with the chemicals that get put in pools.
I believe adding anything through the skimmer is going to shorten the life span of your equipment to some degree.

Matt, assuming you use bleach, do you add it through your skimmer?

If not, how?

I have stated on other posts (and got blasted for it) that sand filters need yearly maintenance to keep the sand clean and in good condition. Backwashing removes the dirt from the filter but does not remove the gunk and clear any channeling or clumping of the sand! Water is going to take the path of least resistance whether you are filtering or backwashing!

To break up the clumps and flush out the sand open the filter to expose the sand and stick a garden hose in it. The sand will loosen up and the water will overflow and carry any dirt and debris. If there are any clumps break them up (a broom handle is good for this but be careful of the laterals or you can break them!). When the sand is clean, free floating in the water, and has no clumps you can stop flushing it and reassemble the filter. If the sand is really dirty or calcified you might want to use a commercial sand cleaner on it.

BTW, Thank you for making my point. I hope the proper people get to read it!

Quote:

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Originally Posted by duraleigh

Very interesting. What are your thoughts are on why it was compacted?

It seems to me regular backwashing should prevent that. Do you think the "grey junk" could have been from not backwashing frequently enough? Have you owned the filter since it was new?
But it doesn't always. That's why I say that a filter should be broken down yearly and inspected!
Oops, just reread your first post. I wonder if the old owner thought backwashing was something he and the wife did in the shower?:D

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A lot of things can cause the sand to gunk up and channel...high calcium levels, large organic load, adding DE to the filter, etc. Backwashing won't remove all of that.

I've tried to make this point before and got blasted for it.

Quote:

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Originally Posted by waterbear

To break up the clumps and flush out the sand open the filter to expose the sand and stick a garden hose in it. The sand will loosen up and the water will overflow and carry any dirt and debris.

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This is a good idea. Even after having opened the filter three times already, stirred the sand by hand and done several backwashings, when I used a garden hose it stirred up a lot more 'stuff'. :p

It would have taken too long to let it run clear, so I put the top back on and then immediately backflushed. The water ran cloudy for much longer than it ever has before, so I guess I got most of it. The sand looked 'right' this time, so I think this beast is finally tamed. :D

Other than fixing this sort of problem, it seems to me that sand could not ever really 'wear out', correct?

Aquarium,congrats on getting it taken care of sucessfully! :D
The sand can wear out, however it takes a long time. Actually slightly dirty, or aged sand, filters better than new, the pathways between the individual grains gets smaller either due to the dirt it's already collected or because the edges get erroded so the sand can 'snuggle up' a little closer to is fellow grains - this allows smaller particles to be trapped. Well cared for sand should last 10 + yrs.

Actually, I once again have to disagree (and I know what I am about to say is not a popular position here on the forum) When the grains get eroded they round off and lose the sharp edges that collect the dirt. There is less turbulance and breakup of the water paths between the grains and faster water flow, hence less filtering ability. I know Ben does not agree with this since he has said that some new filter sand has rounded grains.
A slighly dirty filter WILL filter better than a clean one....this is the same idea as adding DE powder. It makes the water paths between the grains smaller.
My 2 cents!

It did cloud the pool a little after this wash. I might not have noticed it earlier, except I'd run the filter 24/7 for three days doing the alkalinity adjustment thing, and the water -was- super clear before I opened the sand filter and used the garden hose on it. :rolleyes: No matter, it's already starting to clear again.

Down to 100-110ppm from 230ppm after (now) nearly four days of this. I've just been playing with some PVC fittings to convert one of the eyeball returns to a fountain, ten feet in the air and hit the other side of the pool with the water. LOL, the kids like it. :D

Seems like someone didn't like my posts in this thread since I got some negative reputation for it....but my advice seems to have solved Aquariums problem with his sand. No one else seemed to have any advice for him on what to do to fix it. I will gladly take some negative reputation if my advice is useful and solves a problem, even if it is not popular. After all, the purpose of this forum is to help people solve the problems they have with their pools! No one else seemed to be able to step up to the plate and take a swing.

Aquarium, you might want to consider adding a bit of DE to the filter now. It will improve the filtering ability by lodging between the sand grains and allow you to filter much smaller particles. When you back wash the DE will backwash out along with the dirt.

Rangeball, I have a couple ways of adding bleach to the pool, the preferred method is to walk around the pool gently pouring the bleach in about 2' from the wall (as far as you can reach over).
The second is to pour it into the skimmer and let the pump blow it out and circulate it, this is only used when my wife is standing by the car wondering why we haven't left yet, tapping her foot on the ground.
I don't really worry about that second method too much since my plumbing is non corrosive and bleach really does nothing to your filter WRT clumping/channeling etc.

Oh BTW, waterbear, nice sand filter cleaning instructions, IMO, dirt will eventually get all through all your sand since there's no way it could ever just lay on top, since some people dump everything in through the skimmer, that dirt and sand wille eventually bond through all the floculant and other chems introduced through the system. Obviously, your method helped clear up an issue quite well. Mine's on year 3, and still working well, but how will it work after 5 or 7 years.......I'll keep your instructions in mind for future reference.