Sand Filter does not work

[Hardy]

In anticipation of a very heavy rain we pumped three inches of water from our 40,000 gallon inground pool. This was done by using the backwash position on the 2 position valve. After the rain the pool was green and cloudy, so I shocked it. The next morning I began vacuuming, only to find that everything was going through the filter and back into the pool. The sand had been changed earler in the summer and everything had worked perfectly. We tried several clairifiers and products that coat the filter, but nothing helps. As a last resort, I removed all of the sand, checked the internal pipes, and added new sand. Still no luck. It is as if the filter is not there. Pool chemicals are almost perfect, according to two different pool companies, and a service tech from one could find no problems. The leaves are falling and I need to close and cover the pool ASAP. Any suggestions?

Thanks

[Guest]

Valve stuck in the wrong position

[lonestar]

Sand filters often do not filter 100% of algae. The more times a pool is shocked once you have algae, the smaller the particles get. Ideally, turning off the pump for a day will drop all the algae to the bottom and then you vacuum to waste. Many times its necessary to "Floc the pool" in order to make the dead algae drop.

not fun.

Alan

[chem geek]

Assuming the sand filter is working and valves are in the correct position, you can improve the filter efficiency by adding a small amount (usually about 1 cup) of DE via the skimmer. You slowly add it until you get a small rise (1 PSI) in pressure. Just note that every time you backwash, you'll lose the DE and need to add some more.

If you go the floc route, OMNI Liquid Floc Plus has had good results from people who have used it. You do need to be able to vacuum to waste in order to get what is settled to the bottom of the pool out of the pool.

Richard

[PoolsComHelper]

Another thing to consider is the type of sand you used to refill the filter tank. You should only use 50mm filter grade silica sand for pool filters. Any other type of sand will not provide the proper degree of filtration. If you have used the correct type of sand, it might be a good idea to check the sand again inside the filter tank. It should be very clean, even, and completely flat inside the tank. Most filters need to be between 2/3 to 3/4 full to provide the proper filtration effect. If the sand is not level inside the tank, then your sand has "channeled" and the water is actually moving around the sand and returning water to the pool unfiltered rather than passing properly through it. If this is the case, simply reach inside the tank and re-level the sand. Even after checking these items, if the water is still green, then you definitely have a chemical problem in spite of the perfect test results. Whenever a pool is green in color, it suggests that there are more algae spores living in the water than there is chlorine to keep it under control (algae free). A typical first step would be to add a triple dosage of shock treatment, pull water out of pool mostly from the main drain, and see what happens over a 24 hour period. If you see progress, but not full recovery, repeat the process once again right away. Until you introduce more chlorine into the water than there is algae, your green water will remain. In the future, it might be helpful to remember Benjamin Franklin's famous quote, "an ounce of prevention is worth a pound of cure." In this case, the prevention would be to make sure you maintain a solid chlorine reading before a rainstorm hits, and always add additional dosage of a good algaecide before the rain. These preventatives will often prevent a problem from developing in the first place.

Good luck
Dennis The Pool Dude

[Guest]

you can improve the filter efficiency by adding a small amount (usually about 1 cup) of DE via the skimmer

Would adding DE to a sand filtre be better than using floc?

At least the dirt would get caught at the filtre in place of settling to the floor of my pool.

[ongesmate]

Hardy, did you get a result and if so what cured it? I have the problem now on my pool that when I vac the dirt comes back in through the inlets, I have flocked numerous times and vac to waste but has did not cured the problem, I used zero chlor through the pump filter that cleared the water a little but did not clog the dirt up to prevent it coming through, I stripped the multi valve which seems ok, so I then cleared the filter,inspected the laterals and all was ok, placed new sand into the filter, 155kgs as per filter instructions but the problem is still there. What next ?

[Guest]

I have a similiar problem of filter not picking up the algae but appears to push it back into the pool. We've changed sand... new filter spring in handle.. filter multiport.. floc it several times. shocked it over and over pool is still green...

[ongesmate]

Hardy, did you get a result and if so what cured it? I have the problem now on my pool that when I vac the dirt comes back in through the inlets, I have flocked numerous times and vac to waste but has did not cured the problem, I used zero chlor through the pump filter that cleared the water a little but did not clog the dirt up to prevent it coming through, I stripped the multi valve which seems ok, so I then cleared the filter,inspected the laterals and all was ok, placed new sand into the filter, 155kgs as per filter instructions but the problem is still there, can hardly see it returning, just a little cloudy over the deep end inlet but when I finish the vac you can see the pool still hasn't the clarity it used to have. What next ?

[ALL BLUE]

ALL BLUE HERE, ALGAE AND SAND FILTERS DONOT MIX. SAND FILTERS CANNOT FILTER OUT ALGAE AS A RULE. SAND FILTERS WILL ONLY FILTER DOWN TO 40 MICRONS,CARTRIDGE FILTERS 20 MICRONS,EARTH FILTERS 1-5 MICRONS, ALGAE IS BETWEEN 1 AND 3 MICRONS . I CAN CLEAR ANY POOL IN 3 DAYS AND NOT RUN THE SYSTEM. THE POOL IS SUPER CHLORINATED GREATLY DEPENDING UPON THE DEGREE OF GREEN. ALUIM OR ALUMINUM SULFATE 2-3 HAND FULS ,A COPPER BASE ALGA-CIDE AND BRUSH BRUSH, BRUSH, IF YOU ADDED ENOUGH CHLORINE ALGAE WILL BE DEAD TURN WHITE AND FALL OUT OF SUSPENSION. ALL DEAD ALGAE WILL BE LAYING ON THE FLOOR( IN 3 DAYS IT WILL RISE FROM THE GREEN GRAVE), AND READY TO VACUUM TO**WASTE** NOT!! BACKWASH YOU WANT THE DEAD ALGAE OUT OF THE POOL AND THAT WATER TOO. IT IS A VERY SLOOW VACUUM CAUSE IT FLOATS SO EASILY. 35YRS WORKS 1ST TIME EVERY TIME. OH AND MAKE SURE THE CYNERIS ACID IS UP OR YOU COULD LOOSE ALL THE CHLORINE YOU JUST ADDED TO THE SUN. GOOD LUCK ALLBLUE

[I am a poyol pro]

hello,

I have a sure way to free a green pool of algae, maybe once and for all. will post a sticky on it this week.

Luke

[ben_and_ali]

I have a bit of a tip for vacuuming after you've flocked your pool - couldn't find anywhere better to post it so I thought I'd put it here!

If you have a creepy crawly, disable the jittery bits that cause the creepy to crawl, and get in the pool and move the vacuum around by hand. Otherwise the jittery bits will disturb all the flocked particles from the bottom of the pool and spread them everywhere, so you then have to wait for everything to re-settle and do it again. Not good if you live with water restrictions and pumping to waste needs to be avoided as much as possible.

[Wikdy]

Just like to say thanks to ALL BLUE. Looking at our green pool wondering what we could do. Found this posting although it may be old it worked and we are now back in the pool again !!!!! Thanks again for the advice.

[sumonkhan44]

After the rain the pool was green and cloudy, so I shocked it. The next morning I began vacuuming, only to find that everything was going through the filter and back into the pool. The sand had been changed earler in the summer and everything had worked perfectly.

[jenny17]

Hey,

Recently I purchased a sand filter for my swimming pool, but it doesn't work, I am a little bit confused about it what should I do now?
Please suggest me something about a sand filter???