Using Bleach to fight algae

[dstinyz]

Please Help. I have easy set metal frame pool 15x48, 4440 Gallons.

FC- 1
Br-2
PH-8.2
TA- 320
CYA- between 45-50ppm
Total hardness - 520

I have read alot about using regular bleach to fight algae and I have found the BleachCalc. I just have a few questions reguarding this method.

Is it safe to use bleach in a vinyl easy set pool? What do I have to maintain my FC level at to fight the algae? (What is the differnce between FC and TC?)

Do I add the bleach while pump is running and do I have to keep it running the whole time until algae is gone?

[South TX Poolguy]

Yes liquid chlorine is the best for liner pools. Pour it while you walk around the perimeter.

Yes keep your pump running 24/7 while you are fighting algae.

Also backwash or clean the filter twice a day while clearing up the pool.

The chlorine level should be off your scale for 24 hrs. The bleachcalc program should have told you how much to add. I would go with a gallon right at dush then repeat the next night. All living things will be dead.

[dstinyz]

Thanx a bunch! How do you back wash with a easyset pool? There is no setting to do this. I was also wondering when I purchased the pool kit it came with a CHEAP vaccum that you hook to a hose and all the stuff goes into a bag...this will not work to get out the algae because the particles are so small they go through the bag! Can I purchase another vaccum to hook up to this kind of pool? And if so how do you hook it up? Again thank you very much!

[Guest]

I heard that if you put cotton balls in the bag, it will help grab ahold of the dead algae...

Those little sweepers should be ILLEGAL!

[dstinyz]

thanx alot, I will try that.

[jody]

Hi.
This has been helpful. How much bleach is needed to be effective?

Thanks

[Backglass]

Hi.
This has been helpful. How much bleach is needed to be effective?

Thanks

Bleach is chlorine. Chlorine is bleach. Assuming your pool water is balanced, keep your pool at 3ppm chlorine at all times, and higher (10+ppm) to shock after rain or a large bather load...especially kids & babies. Use your test kit to check levels.

[jody]

Thank you so much!

[chem geek]

Wherever you pour your chlorine, do so VERY slowly. Personally, I think it's best to pour very slowly in front of a return in the water flow, but mixing up the water with a pool brush near the bottom of the pool will help as well (others say pouring into the skimmer works, but I think the water flow from the return jet at the deep end is best). Above-ground pools typically have very poor circulation near the bottom of the pool because they usually do not have floor drains. Bleach and chlorinating liquid is heavier then water so unless it dilutes in a vigorous water stream (return jet), it may sink to the bottom and can fade or degrade the vinyl liner.

Pre-diluting the chlorine in a bucket of pool water and still pouring slowly will help. This is similar to what needs to be done with Cal-Hypo as it does not dissolve quickly so adding it to the main body of pool water will often have it settle at the bottom and cause fading and degradation.

[Jack Sparrow]

I've got an algae bloom right now and will be treating it this evening. The one thing I find frustrating on this site is there doesn't seem to be a general concensus on what chlorine levels should be, during the shock period, to kill an algae bloom. Some say 10ppm, while others say 15ppm.

Can anyone give some good hard science on what level to shock at to kill an algae bloom.


Thx

[dstinyz]

From what I have read it should be 40% of your CYA until it holds that level for 24 hours on its own then it should be kept at 11-11.5 of your CYA. However from my understanding if your CYA is to high( well over 50) it is hard to fight the algae and the only way it seems you can lower your CYA is by draining some water and adding new water.

[Backglass]

From what I have read it should be 40% of your CYA until it holds that level for 24 hours on its own then it should be kept at 11-11.5 of your CYA. However from my understanding if your CYA is to high( well over 50) it is hard to fight the algae and the only way it seems you can lower your CYA is by draining some water and adding new water.

That is correct. There is no standard because it varies, depending on your CYA level. Chemgeek has created a "best guess" chart for this but it's not in it's usual location. I am sure he will be along soon and post!

[Guest]

From what I have read it should be 40% of your CYA until it holds that level for 24 hours on its own then it should be kept at 11-11.5 of your CYA.

Jeez my cya is around 100 at the moment but how on earth would I get chlorine up to 40

[Poolay]

The hard science is it will differ when you consider the variables of the specific situation being treated.
Don't over-think it, over-shock it instead.

[chem geek]

If you use a lower Free Chlorine (FC) level then it takes longer to kill the algae. If it's lower than about 5-10% of the Cyanuric Acid (CYA) level, then the algae can grow faster than the chlorine can kill it and most likely this is what happened in the first place to let the algae bloom get started. The guideline of an FC of 40% of the CYA level is for a reasonably fast kill. See Defeating Algae for more info.

When the CYA level is very high, such as 100 ppm or more, then it's usually a good idea to do a partial drain/refill to dilute the water to lower the CYA level since that's something you'll have to do eventually anyway at some point. During this time, if you want to kill some of the algae or at least keep it in check, you could use chlorine -- perhaps at 20 ppm FC if you don't want to go up higher until after you've gotten the CYA lower.

Before you add the chlorine, you should lower the pH first to around 7.2 or slightly lower. The addition of large amounts of hypochlorite sources of chlorine will raise the pH -- as the chlorine gets used up, the pH will mostly drop back down.

There are other methods of killing algae after a bloom, including using a copper-based algaecide, but they result in side effects, most notably a risk of staining especially if the pH or copper levels get high.

As for getting the chlorine level up, this is easiest to do using chlorinating liquid, though 6% unscented bleach (e.g. Clorox Regular) will work as well. One gallon of 12.5% chlorinating liquid in 10,000 gallons raises the FC by 12.5 ppm. One 3/4-gallon jug of 6% bleach in 10,000 gallons raises the FC by 4.6 ppm. So you'd be adding multiple gallons of chlorinating liquid or many jugs of bleach. If your pool is low in Calcium Hardness (CH), say because it's a vinyl pool, then you can use Cal-Hypo as a source of chlorine. Just keep in mind that for every 10 ppm FC added by Cal-Hypo, it also increases CH by 7 ppm.

See this link for how a pool gets cleared using chlorinating liquid or bleach alone. This was a person's pool upon spring opening when the pool was "let go". Larry is in the process of cleaning up a pool here so should have some more pictures showing how algae can be killed and cleared with chlorine alone. The key is maintaining a shock level of chlorine, regular brushing, constant filtration, and periodic backwashing (or filter cleaning, depending on filter type).

In the future, you have choices to make. Your CYA level probably got high because you were likely using Trichlor pucks/tabs and maybe even Dichlor granules for boosting chlorine levels. For every 10 ppm FC added by Trichlor, it also increases CYA by 6 ppm. For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm. If you want to use these stabilized chlorines, then you need to either increase the FC level as the CYA level climbs over time (which is hard to do with these products as it just accelerates the rate of CYA rise) or you need to use a supplemental algaecide (e.g. PolyQuat 60 or a phosphate remover) to prevent algae growth. Using unstabilized chlorine with a fixed amount of CYA already in the water is the least expensive way to go, but is less convenient since you need to add chlorine every day or two (unless you have a pool cover in which case you can usually add it twice a week). There are ways of automating chlorine dosing including use of a peristaltic pump or The Liquidator (but can have scaling issues) or a saltwater chlorine generator (SWG) system.

Richard