Decision on Zeobrite or Sand replacement

Ben - Great to have the forum up again, thanks for the work that you don't get enough credit for!

So, my above ground is 6 years old this year, 18x33 w/deep end (~15k gals).
Very warm winter in TX, added some bleach now and again and let it turn a bit green. No problem, except that it got warm quick and turned green-Er! Last couple weeks I've been vaccuming to waste the dead, white algae. Bleach, bleach & bleach, but the problem is just like some other posters, the fine algae is going through the sand filter.

That leaves a milky-white pool which I've been vaccuming every day and haven't seen the bottom of for 2 weeks (plus pump running 20hrs /day). I have the cleanest fine, bleached, dissolved algae south of the Canadian river! If I can only get it out of my pool without emptying it, which is another thing. Can't really vaccum too much to waste anymore, my water bill is bigger than my mortgage. I've tried clarifier but it doesn't do much.

So, do I replace the sand with new sand, or ZeoBrite?
One concern with Zeobrite is that I run a SWG and have read that salt is used to 'clean' ammonia from the ZB. Doesn't matter to me but --
Can you (Is anyone) using Zeobrite with SWG?

Thanks and hope to post pics of my soon-to-be sparkling pool! (It's gonna be 97 tommorrow!
Tom

Don't know if this will help you but zeolite filter medium (which is what Zeobrite is) has been used in freshwater aquariums for many years now precisely for it's ammonia scavaging properties. It is not used in salt water aquariums because the ammonia scavaging properties are greatly reduced in salt water and the salt CAN release the ammonia compounds from the zeolite that have been trapped back into the water (usually when pH drops) which can prove lethal to the livestock. It seems to reason that the same might happen with a SWG although the salinity is about 1/10 of seawater. The cleaning procedure for Zeobrite is a very concentrated salt solution/sand cleaner mixture that is acidic according to the company's website. The result if ammonia is released back into the poolwater might be combine chlorine although this is just conjecture on my part... there is a possiblity that at normal pH and salt levels in a pool with a SWG there is no noticable effect at all.
An interesting question!

I'm running an SWG (3200 PPM) and Zeolite in my 26" Pentair Sand Filter. The pool is 26000 gallons. I have not noticed any combined chlorine and the water has been crystal clear since the pool installation in early March this year.

I keep the PH in check with Muriatic acid, FC at 3PPM and stabilizer at 40PPM. We swam for the 1st time this year yesterday. The air temperature was 93 and the water temp was 81 degrees. Very refreshing..:) I had a hard time getting the kids out of the pool...

Hi, Tom,

Man, it seems like sand filters are taking a beating on the forum this year.:( :(

I would submit that any properly operating sand filter is capable of keeping a pool sparkling all year round. They have been around for decades and, if there was a fault in them (like the inability to filter dead algae, red dirt, etc.) they would've gone the way of the Edsel.

So, I'm thinking it might be a little premature to blame the filter. What are your numbers for FC, CC CH, pH, Cya? I'd make sure I was starting with balanced water and then look for some mechanical issue in the filter.....about the last thing I would look to do is put in Zeobrite...sand has worked too long, too well, for too many people.

I would try adding a cup of DE while the system is running. The DE will settle in the sand filter and trap a lot smaller particles. I did this once and have never had to do it again.

Thanks for the ideas.
Waterbear - That's what I was thinking, ammonia. But as it stands now all the ammonia Does pass thru the filter so any ammonia caused to be released from the z-lite by the low % salt solution won't really affect the overall chemistry.
gwrace - Same answer; I don't think it has much, if any effect; SWG & Zeolite
Duraleigh - That is where my post came from - 6 year old sand and we run pumps pretty much year-round here in TX - So figure 3x the time of most 'normal' run times in colder climates. Though I haven't done a complete work up on the water using my PoolSolutions kit, the fact is that you can see the dead algae come through the return nozzle when vacuuming deep end where most of the algae settled, it's a 'cloud'. Very, very fine.
Hence the original question - Time for replacement sand, or zeolite?
Remember the filter has worked fine until this winter/spring, and it appears the filtering ability now reduced. Pump pressure is fine, all is operating as normal except that it's not 'filtering' the fine, very fine particles. No sand is coming out, so no laterals are broken or anything like that. And when backwashing it does expel bugs, dirt & the like so it is filtering large particles.

Duraliegh/brock - Thanks. I am leaning that way.
I have asked several pool stores about adding DE to the sand but they never heard of it. Though they have heard that their $23 Sand Filter Cleaner works well ;-)

I have decided to replace the sand.
Will update everyone later.
(100+ today in Austin! with 'rolling blackouts', time to leave work early & swim!)
Thanks everyone.

I would agree with the leave work early part. I work in Round Rock. The heat extremes this year are strange and it's way to early in the year for 100 degrees plus. The rest of the week is supposed to be in the mid 80's.

The rolling electrical blackouts are another story...:)

Hi, Tom,

If it's possible, try to eliminate all the other variables when you change the sand and let us know what you find out. After saying that, I have no idea how you can retain the dead algae in your pool while you change sand but maybe we'll all get an indication if your effort was effective. Good luck with it and let us know :) :)

Dave S.

Ammonia is released into a chlorine filled pool if you use an SWG? Excuse me, but doesn't mixing ammonia and chlorine result in a deadly gas being produced, which is why you are warned to NEVER mix the two for home cleaning?

If you put DE in your sand filter, you'll probably have to add more every time you backwash. Since you only add a half/cup to a cup, a 10-15 lb box should EASILY last the season. I use this method as well and like it.

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Originally Posted by CarlD

Ammonia is released into a chlorine filled pool if you use an SWG? Excuse me, but doesn't mixing ammonia and chlorine result in a deadly gas being produced, which is why you are warned to NEVER mix the two for home cleaning?

If you put DE in your sand filter, you'll probably have to add more every time you backwash. Since you only add a half/cup to a cup, a 10-15 lb box should EASILY last the season. I use this method as well and like it.

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The ammonia will be in the form of ammonium ions. These are what combine with chlorine in the pool to form chloramines (VERY simplified chemical explanation!)
From my understanding some "old time pool service guys" would put anhydrous ammonia and liquid chorine into a pool to purposely form chloramines and then reach 'breakpoint' by putting more chlorine in 24 hours later. The chloramines are eaten by algae and decolorizes it. Some commercial algae products also put ammonia compounds into the water for the same reason (Black Algaetrine comes to mind)
Also many water treatment facilities put ammonia or ammonia compounds into the water with the chlorine to form simple chloramines to prevent the formation of more toxic ones. (this has been a major headache to every aquarium hobbiest for years now and forced us to learn all about "breakpoint chlorination" even if we never owned a pool!:D since ammonia is MUCH more toxic to fish and other livestock than chlorine is and choramines are MUCH harder to get rid of then chlorine.)

But you are right, mixing liquid ammonia and liquid chlorine CAN release deadly fumes and should be avoided! The difference is most likely the dilution factor involved.

Thx waterbear. I really didn't want to start to explain that saltwater is the recomended cleaning agent for zeolite, and when it 'cleans' the zeolite it is widely known that it releases stored ammonia from the zeolite. Therefore, if you're running a swg constantly, the zeolite is constantly being 'cleaned' then ammonia is constantly being released. Obviously it will be in such minute amounts, and dilution as you point out below, that it will not be an issue what-so-ever. And to take it to a farther logical point, will zeolite ever be able to 'absorb' any amount of ammonia if saltwater is passing over it?
Which makes the whole question of ammonia release kinda moot.
My issue was that I didn't want to invest in z-lite if this cleaning ability is one of it's strong points and I was stifling it by using the media in an swg pool.
I'm replacing my sand anyway so it doesn't matter.

Guess we did end up 'splaining it, Lucy!
Tom

UPDATE: Replaced 250lbs of sand saturday, April 22. Today, water is 85-90% clear and clearing nicely. Added 2x40lbs bags of salt, SWG is running at 3000ppm salt level and generating nicely. The surface of the vinyl is very rough, must be algae that scaled on there. It won't come off with a stiff poly brush, but will come off with some gentle wipes with a 'green' pad. Anyone ever run into this? Guess everyone will get a green pad to wear on their feet for a week's worth of swimming!
Thanks for the tips, tricks and 'listening'.
Later
Tom

Hi, Tom,

Thanks for the follow-up. That's a very interesting comment about your vinyl liner.

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It won't come off with a stiff poly brush, but will come off with some gentle wipes with a 'green' pad.

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I'm not positive, but I don't think that's algae. When I review your first post, I see this:

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but the problem is just like some other posters, the fine algae is going through the sand filter.

That leaves a milky-white pool which I've been vaccuming every day and haven't seen the bottom of for 2 weeks

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Combining those two observations makes me think that something precipitated out of your water and has scaled on the vinyl.....perhaps calcium.

To my knowledge, algae dead or alive doesn't create a scaling condition. Nor does dead algae turn a pool milky white (to my knowledge)...more like cloudy grayish blue.

Well, if your water looks nice, that may be enough. I believe I would look at my test numbers very carefully....I think there was something else going on. Have you done a complete test this Spring?

Dave,
I think there may be some calc precipitated out.
I tested about 3 days after I went back to regular chorination (during/after sand change my FC was +15) and we went clear.
According to my handy-dandy ps233 -
FC=3.5 CC=0 TC=4 pH=7.8 Alk=190 Cal=240 Cya=0 (week ago)
I retested 2 days ago FC=4 CC=0 TC=4.5 ph=8 Alk=210 Cal=270 Cya=20

The calc is coming off with a green pad but the 'gentle wipes' in some spots translate to "you gotta scrub".
Since I run a SWG my ph is always high, and were in central TX, nothing but the best mineral water in the west. Filtered by the limestone rocks and pumped out of the aquifer, clogging shower heads and coffee pots in a city near you!

Anyway, I'm not looking for quick fix, I know this will take work, But if you know of anything that could help soften up some of that calc to make it easier when scrubbing every inch by hand please pass it on.
Oh, and since were very far (weatherman says ~20") behind in rainfall for 12 months running, every week I just add more of that mineral water back to the pool for top-off, durn.
Thx all,
Tom

Hi, Tom,

I wish I could offer some practical advice for getting whatever it is off the wall.....I just have no experience. Home Depot sells "sulfamic acid" a very mild acid for cleaning masonry.......I just don't know if it would have an effect on your liner if you brushed a little on. Smarter folks than me may have an opinion.

Yeah, your pH and Alk numbers are up there pretty high.....very conducive to scale formation. Adding some muriatic acid would help a lot

I believe I would work on reducing pH to around 7.2 - 7.6 and Alk down to the 90 -120 range........that would probably prevent you from ever geting back into that scaling condition.

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I have asked several pool stores about adding DE to the sand but they never heard of it. Though they have heard that their $23 Sand Filter Cleaner works well ;-) :D :D

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Sounds like your water is looking pretty good....nice work. I do believe you need to add some muriatic, however. :)