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An extra-long winter means the cover’s been on the pool, keeping the algae safe and warm. It’s time to uncover and get the water crystal clear, ‘cause you’ve earned a dip in the deep end after all the springtime snow shoveling. When the algae refuses to get out of the pool, the forum tells you how to get the job done.

Original Post: Cloudy/Green Pool

tada2 Member

I started trying to kill the algae in my pool 2 weeks ago. I've spent at least $400 in chemicals, bought new cartridges for my filter, pressure washed those cartridges twice already and I still can't see the bottom of my pool or hot tub. I can now see the 2nd step in the pool and the seat in the hot tub. I don't know what else to do. Do I just keep cleaning the cartridges every few days or do I keep using more shock and algaecide. I just ordered swimtrine 7.4... What’s the difference in that and swimtrine plus?

ph. 7.4
ta 70
chlorine 4.0 (I’ve used 16 bags of shock in 2 weeks)

Shadeladie Super Moderator

Hello and welcome to the forum!
Until the expert comes along, have you vacuumed and used a pool brush to scrape first?
When I used to have a pool, that's what needed to be done first, then I ran the filter and used chemicals to get rid of the particles left floating around.

Pilot Dane Group Moderator

How large is your pool? Have you been able to get your chlorine level higher than 4 ppm? Specifically what shock are you using? You say $400 in chemicals and 16 bags of shock, but the only thing you mention by name is an algaecide.

Be vigilant cleaning your filters. If the pool is really gunked the only way the algae is getting out of the pool is by you hosing it out of the cartridges.

tada2 Member

Thanks... good to be here. Yes I brushed and scrapped the entire pool before I started. I brush it a couple times a day. I also have a dual speed filter. I've been running it on high for 12 hours a day and on low for 12 hours a day.

I was using shock I purchased from Leslies Pools. My Pool is 17,000 gallons. Yes, my chlorine was well over 6 ppm at one point. I ordered a Kemtech shock from Amazon. That will be in on Wed.

I've tried an algaecide I bought from Leslies, yellowout, and an aqua kem 60%. I also bought muriatic acid for ph, alkalinity up, calcium hardness, conditioner/stablizer, phos free, chlorine tabs, clarifier, and I'm sure I am forgetting something. I've had my water tested at the pool store several times and my levels are all spot on, except the phos level because I can't put that in until the algae is out. You would think 3 algacides and 16 bags of shock would kill the algae. My water is no longer dark green more like a greyish teal color. I bought new cartridges before I started this process and have pressure washed them 3 times since. I even bought a vacuum and a hose, but took that back when I couldn't figure out how to get it to get good suction. I called a pool guy to see if he could come and vacuum it and he said it needed to be clear first/see the bottom.

Pilot Dane Group Moderator

If your filter cartridges are rapidly clogging with algae that could be the cause of poor suction in your vacuum. You may have killed the algae with all the chemicals you've added and it can simply be a matter of how long it takes to filter it all out of the water. Pleated filters can clog pretty quickly. I have two sets so I can pull one set out and put the clean ones in.

Once I tried filling my pool with pond water (very fine silt and algae). I'll never do that again. I quickly got sick & tired of changing and cleaning cartridges for over a week.

todrut Forum Topic Moderator

You want to take out the cartridges of filter but keep pump circulating till you kill the green, if there is leaves and debris in bottom of pool you will need to scoop it out with leaf net. After most debris is out then you want to super shock pool, I'll tell you the schedule. Don't waste your money on any other chemical right now except chlorine. Make sure pump is circulating and returns are pointed down toward main drain not up (but no cartridges) make sure chlorinator is filled with tabs and on high.
You are going to use a lot of shock again. What is happening is the algae is eating the shock faster than it can kill.

Is pool vinyl, fiberglass or concrete?

lawrosa Group Moderator

I use the BBB method. Pool chemicals cost me possibly $80 bucks for the whole season. BBB is bleach, baking soda, and borax. It’s the same ingredients as the pool store stuff. Baking soda for the alkalinity and borax for the PH. These products raise it. Bleach is the same as chlorine only salt based. Sodium hypochlorite.

Run pump on low 24/7

Aside from the algae eating your chlorine you need to check your cynaric acid level (stabilizer). This level should be around 30. If too low the sun will eat the chlorine in a matter of hours. Too high and your shock levels will need to be higher as well as your daily chlorine levels.

Here is the chart and what your shock levels should be.

Pool chemestry chart



So the normal operating range is 30. That means your shock level is 12. You must maintain this shock level until the chlorine hold overnight. That means checking hourly, and raising it back to 12 when it drops.

To get a 17000 gallon pool to 12 from 0 chlorine level you will need 423 oz of bleach. That’s about 3.3 gallons. Then check hourly and add more bleach. That is if your CYA is a 30...



tada2 Member

My pool is concrete. So run the filter with no cartridges? Then where will the dead algae go? If I choose to filter, should I clean them daily?

lawrosa Group Moderator

So run the filter with no cartridges? No that’s absurd. Actually you clean the filter when the psi gets 5-8 psi over start psi with clean filter.

tada2 Member

Thanks everyone. I'll keep at it! My sons will be home from college for only one month and that is May. So I was trying to make sure it was ready for them.

todrut Forum Topic Moderator

You want to kill the algae before trying to clear pool. So you want it stirred to kill the green. Cartridge in filler will just keep the algae in bloom. You can't remove algae as long as it is alive. When water is milky white then you want to focus on clearing, but hey I've only been in the business for 24 years...

lawrosa Group Moderator

Cartridge in filler will just keep the algae in bloom. You can't remove algae as long as it is alive. Shock level will kill algae in the filter as well, no?

I believe he has a CYA issue and not using proper shock levels... Like a yo-yo.

Pour the bleach into the skimmer. What are you using pucks? They contain CYA and years of use raise levels well over 100+ from what I have seen. That would mean you need a shock level of 39 ppm. And if so you’re probably not shocking the pool high enough.

I cannot over emphasize about proper testing of what’s important to get your pool clear...

I have had pools all my life. 30 + years. Save money use BBB... Saves time also....

Just my opinion.

tada2 Member

My cya is 20. I'm actually holding off on raising it to 30 until I clear all of the algae. Yes, I have been using pucks. The water is clearing, just very slowly.

grandbabs Member

Starve the algae!

The algae are growing so profusely because they are well fed: eg, fertilizer runoff or aerosol from sprays or lawn treatment; animal "fertilizer" (Ducks in my case. I actually have black bears in my pond. They don't always "go" in the woods.)

You have to find the nitrogen &/or phosphate source and eliminate it. Otherwise, you are fighting a losing battle. And yes, lots of scrubbing of the sides, cleaning filters, etc.

Chlorine, i.e. bleach, attaches to lots of organic material, i.e. substances derived from living cells. So, dumping a lot of bleach into a pool full of algae, even dead algae, neutralizes a lot of the chlorine. So step one is physical removal of as much algae as possible - scrubbing and filtering.

Is it practical to drain the pond, scrub the liner then refill?

Also bleach/chlorine products, esp if liquid, must be fresh. Old bleach will break down. Borax and baking soda are also good. In fact, if you can drain the pool, while the sides are damp, you could use the baking soda as a scouring powder to help with the scrubbing. And wipe/rinse out all the scrubbed-off debris-- the dead algae will break down and fertilize the new crop!

Algae are in the soil and water and are blown in wind too. You can't get away from it. all you can do is starve it to minimize it and poison the rest with bleach, etc.

duraleigh99 Member

To defeat algae, you must kill it first with adequate chlorine and maintain that chlorine level until your pool is completely clear.

Adequate chlorine depends upon the level of CYA in your pool. You need your CYA test result and refer to the chart lawrosa published. That high value is the chlorine value you will need and you must CONSTANTLY bring your chlorine back to that level or the algae just keeps growing.

You cannot filter live algae out of a pool... you must kill it first.

The second part of getting your pool crystal clear then becomes filtering. All that dead algae will clog your filter VERY quickly at first but the intervals between cleaning will get longer and longer as your filter does its job.

Read more advice at: //www.doityourself.com/forum/pools-spas-hot-tubs/493257-cloudy-green-pool.html#ixzz2RP9Db2BV

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