Lets face it, every pool will experience green water at one point or another. The main mission when this takes place is two fold. The first is how to treat the water as effectively as possible to get it clear again as quickly as possible. The second item that needs attention is we want to make it happen without breaking the bank. If you go down to your local retailer there’s more shocks, phosphate treatments and water clarifiers than one knows what to do with. Not to mention the countless “novelty” chemicals that are available that can cost an arm and a leg!
When treating green swimming pool water, there are 4 key steps that need to be addressed. Let’s dive in!
Treating green swimming pool water step #1: Circulation. Water circulation is an absolute must. You can add all the shock and other chemicals you want, but if water movement isn’t taking place, it won’t change the look of the water. While you’re turning the pool around, run the equipment 24/7. For most standard residential swimming pools, this will allow for about 3 full water rotations. Meaning, that all of the water will have gone through the filter about 3 times.
Treating green swimming pool water step #2: Shock treatment. Ideally, shoot for a granular shock because it has the fastest reaction time. I’d recommend using HTH Super Shock that contains at least 65% available chlorine. The more available chlorine, the more effective (and faster) it will be in the pool water. It’s important to stress that one cannot over shock a swimming pool. Depending on how green the water is, I’d recommend starting with 3-4 lbs of shock, wait 2-3 hours, then check what the water looks like. There’s no need to test the water at this point using a test kit as the results will be meaningless…regardless how much “free chlorine” it’s showing present.
Treating green swimming pool water step #3: Filtration is key. The more effective the filter is throughout this process, the faster the water’s going to get clear again. The best way to ensure this is taking place is to backwash/clean your filter several times a day. You cannot over-backwash your filter. If you’re using a DE or sand filter, place the multi port valve in the backwash position and let it run for around 90 seconds or until the water is clear. This may take a bit longer depending on the duration of time between backwashes. If you have a cartridge filter, remove the dome of the filter (typically, there’s a band clamp that needs to be removed), lift the cartridge filter(s) out of the filter unit and thoroughly clean it.
Treating green swimming pool water step #4: As the water begins turning clear (still may be cloudy, but blue (not green), begin administering a quality water clarifier. This will speed up the process to getting clear water again. I’d recommend adding it the first time immediately once you notice the water is blue and not green, then again about 12 hours later. During this process continue running the equipment nonstop. During this time you should also be stabilizing the pH and Total Alkalinity levels. I wouldn’t worry about testing or adjusting free chlorine as it’s likely going to be elevated for a few days while the water adjusts, but it is important to test and adjust your pH and TA levels.
I hope you’ve enjoyed these 4 steps on getting your water cleared up as quickly as possible. Using this system, it’s possible to turn your green swimming pool water around in 48 hours or less!
{ 16 comments… read them below or add one }
Perfect timing for this article! It’s just getting warm enough to a point where people are reluctantly pulling off the insulating cover and finding green water. =)
I have an above ground 24 footer. Although my pool is still covered up, I’ve decided to open it at the end of April, keeping it covered with the solar cover. My dilemma is, I have to use city water to fill lit back to the top (it’s lowered to under the return line). I replaced my liner last Spring and filled it up – and fought algae ALL SUMMER. Found out that the city has quit using chlorine to treat the water, so we had algae problems in the city water. What would be the best way to treat the water once I get it filled? I certainly don’t want to go through that again!
My problems come from a constant 2 months nearly of yellow pollen falling from trees. And of coarse from the yellow it goes to an old black and it stains the pool if I miss any on the vaccuuming. Of course from this comes the mustard algae. I can not work this pool enough this time of year it is constant skimming and vacuuming. In this area the water warms pretty fast and swimming normally starts earlier. We also have our hot tub connected to the pool. Is there a way I can just run and filter my hot tub this time of year and get the pool a little later? Or is this advisable?
Thanks so much,
Sharon
Hi Sharon,
It really depends on how the plumbing is situated to run the hot tub & swimming pool. Often, there’s separate equipment for each body – if this is the case, you can run each independently of the other. If not, you’ll need to make sure you’re maximizing water flow with the current setup. The likely issue is not so much as to running the equipment separately, but one caused by phosphates.
2 things that may help…
1. Maximize flow to the hot tub and the pool. Make sure the suction/return lines are adjusted so there’s adequate water movement in both bodies of water.
2. Use NoPhos or a comparable product to attack the phosphates and remove the food source of the algae.
Terry
@ Betsy,
I can understand the frustration. This is a cyanuric acid (conditioner) issue. Once you top of the water add cyanuric acid to protect the chlorine. This will keep it protected from the sun to eliminate/reduce any algae issues (assuming the free chlorine is adequate).
Terry
I have been strugling with green tinted water for about 3 weeks my neighbours pool is crystal clear. Having put the normal amount of chlorine into the pull each week. I put Chlorine shock in and left it running for the day. Bingo crystal clear water again.
I’ve been blessed by three consecutive swimming seasons of perfectly clear water. I attribute this to :
1) A high quality pool cover that lets water pass into the pool but does not permit any light tp penetrate.
2) On the very day that the cover is removed, clean filter cartridges a installed into the filter and the pool equipment is started as soon as the pump is primed.
3) I have an automated chlorine measurement and dispensing system that creates chlorine from salt water and uses Ozone to oxidize any remaining chlorine byproducts. All I need to measure on a weekly basis besides the normal tests is to measure the salinity.
4) My system measures the PH and adjusts it by adding CO2 as needed. I used 1/4 of a tank last season.
So far, either I’ve been lucky, or I’m doing the right things.
tried a new hth product.. ..called green to blue.. ..at wal-mart($13.) ..works as promised!
Green to Blue is only for sand filteration systems.
I read the information you provided regarding Green Swimming Pool Water. Thank you so much for making your research data available to us. If I ever buy a pool, I will know what to use to safely keep the pool clean.
Hey Terry, I have previously used your books to cure my green above-ground pool. This year we had thought our pool liner was going to have to be replaced since we had extensive leaking last summer, so we waited for the water to leak out over the winter (did not cover pool). The water level is high now (why??), so I decided to try to salvage the pool, but can’t turn my pump on until I get the debris out of the pool….I tried using my nets and hose with leaf basket to remove leaves but can’t even see the bottom. Is this worth pursuing, or would you advise draining the pool and starting over? It is REALLY green and murky this time…can it be saved?
Hi Susie,
Tough to say without knowing all the variables or how much debris is in the pool. Assuming it’s less than about 6k gallons, it’s likely a lot less expensive and time consuming to drain the water and start from scratch.
Terry
Thanks for your article! It’s always scary to pull off that cover for the first time in 6-months. It’s nice to know I can treat the water without calling someone.
Hello Terry,
I am a manager of an apartment complex and recently I lost my maintenance man, As a result this has made me responsible for the pool. I know absolutely nothing about pools. I was absent from work for a week and upon my return I discovered that my pool had turned the color of a deep green,(Algae). I first tried to salvage the water before I had to drained the pool. After I drained the pool I had to take a shovel and shovel the algae out of the bottom of the pool. After I drained, scrubbed and refilled the pool with water, I turned the pump back on and as the water began to shoot out of the water jets inside the pool I noticed the water that was shooting into the pool was green. Therefore, my water is green again. Its not as green as it was in the beginning but I do have a light green tint. How do I rid my pool of the light green tint? HELP!!!!
Vanessa K
Hi there, thanks for another great article. As a professional pool builder, we appreciate that our customers can get this kind of information, and solve this problem without having to call us first.
Hi there, thanks for another great article. As a professional pool builder, we appreciate that our customers can get this kind of information, and solve this problem without having to call us first.