Will Draining Water Help With Algae?

The main benefit of liquid chlorine is that it is only adding chlorine (plus water and a little salt). For the solid forms, the concern is with the calcium and/or stabilizer which can build up with regular use and cause issues.

The marketing guys for these also like to add ingredients so they can add buzzwords to the packaging to get you to buy. The worst is stuff with "blue" mixed in which is copper. While copper does kill algae fairly efficiently, it doesn't do anything for the bacteria and other stuff you want killed in your pool. Copper also is the stuff that turns hair, swimsuits, etc green. If you get enough copper in your pool, it will even cause metal staining. Google copper staining on here and you will see lots of fun.

Liquid chlorine is a bit less convenient, but it will save you lots of aggravation in the long run.
 
Gotcha. Sorry for the dumb question here, but is the main benefit of liquid chlorine just that it’s easier to mix in the pool water since it’s already a liquid? In the end, 10% chlorine in a 128 ounce bottle is more chlorine than 54% of a 16 ounce bag, so I guess the liquid does have more of the chemical, thus probably does a better job of sanitizing.
No, the liquid just doesn’t have other stuff in it that causes problems. $9/gallon is pretty pricy but is the normal for Home Depot at the moment. Might try Walmart or a pool store and see if they can do any better.
 
No, the liquid just doesn’t have other stuff in it that causes problems. $9/gallon is pretty pricy but is the normal for Home Depot at the moment. Might try Walmart or a pool store and see if they can do any better.
Just ordered for $5.47 from WalMart!

If the “other stuff” that causes problems is stabilizer and calcium, what’s the harm in adding that? Doesn’t the pool regularly need those? Or is it just too much that’s added with the granular chlorine?
 
  • Like
Reactions: Mdragger88
Just ordered for $5.47 from WalMart!

If the “other stuff” that causes problems is stabilizer and calcium, what’s the harm in adding that? Doesn’t the pool regularly need those? Or is it just too much that’s added with the granular chlorine?
It is all about balance. Pools need CYA, and plaster pools need some calcium. The problem is that the chlorine is consumed by the pool and goes away, but the calcium and CYA stays in the water and will build up over time with continued use of solid chlorine.

Too much calcium will cause white scaling along the tile line and water features. Too much CYA will cause your need for chlorine to grow until you cannot keep up and you will end up with an algae nightmare.
 
Just ordered for $5.47 from WalMart!

If the “other stuff” that causes problems is stabilizer and calcium, what’s the harm in adding that? Doesn’t the pool regularly need those? Or is it just too much that’s added with the granular chlorine?
What JJ said above. The other stuff doesn’t go away.
 
It is all about balance. Pools need CYA, and plaster pools need some calcium. The problem is that the chlorine is consumed by the pool and goes away, but the calcium and CYA stays in the water and will build up over time with continued use of solid chlorine.

Too much calcium will cause white scaling along the tile line and water features. Too much CYA will cause your need for chlorine to grow until you cannot keep up and you will end up with an algae nightmare.
Very helpful! Thanks!

In the past, I’ve purchased CYA increaser. In fact I just added some to the pool the other day. I’m guessing that buying and adding CYA is probably not necessary as long as I maintain proper chlorine levels. Is that accurate?
 
Last edited:
If your CYA is low, then it is certainly okay to add it. Was yours low?

Here are a couple of articles for you:
1. ABCs of pool water chemistry - This is a good overview/intro
2. Recommended pool levels - The recommendations for each element based on your pool type.
3. FC/CYA Relationship - The amount of CYA will determine your required chlorine level. Note pool stores still use an older methodology that does not account for CYA, so these recommendations will be different from what you might see elseware.
 
Thanks for sharing! Yes, the CYA was low, so I added one pound to see how it would do. No issues I’m aware of, but the pool is still green and cloudy.

The LC should be here soon, so I’ll try adding a gallon per day to see if that helps.
 
Ok, perfect. Since you are doing a SLAM, and your CYA determines your chlorine required, I would not add any other CYA until you have a clear pool.

The green and cloudy will only be cured by chlorine to kill the algae and your filter to filter out the dead algae particles. Just be prepared, you will probably need to keep your pool at SLAM level for a week or maybe longer.
 
Ok, perfect. Since you are doing a SLAM, and your CYA determines your chlorine required, I would not add any other CYA until you have a clear pool.

The green and cloudy will only be cured by chlorine to kill the algae and your filter to filter out the dead algae particles. Just be prepared, you will probably need to keep your pool at SLAM level for a week or maybe longer.
Ok thanks. Does that mean the chlorine will be extremely high for that whole week period? And I’m guessing no swimming during that time.
 

Enjoying this content?

Support TFP with a donation.

Give Support
Ok thanks. Does that mean the chlorine will be extremely high for that whole week period? And I’m guessing no swimming during that time.
Yes, it will be high during that time until all of the algae is killed. Think of it as sanitizing your water for a week or so. A bit of a PITA, but you will never have to deal with algae ever again assuming you kill it all now and maintain the correct chlorine levels in the future.

As for swimming, it is totally safe to swim in the water at or below SLAM chlorine levels. The one piece of advice we give is that you need to be able to see the bottom of the pool before getting into the pool. That is about swimmer safety in case someone hits their head, sinks to the bottom, etc. and nothing to do with the chlorine level.
 
You still plan to drain your pool in about 10 days to do some repairs?
Once you drain, all of your levels will change, which is why you need your proper test kit to test the water upon refilling.
Only add Chlorine now because we are trying to keep the algae issue from getting worse. Remember to do 2 things prior to draining your pool. 1) backwash your sand filter to rid it of any algae that it may have captured and 2) brush the pool really well to stir up the algae and let it drain away
While your pool level is down during the repairs - you can take a brush to scrub any areas you see that may be problematic.

Once your pool is full, test it and report back those numbers - the critical ones are pH, CYA, FC, CC and TA. Based on the results you then will commence the SLAM. We want your pH to be in low 7’s so have some mauratic acid on hand if needed. You will bring the FC up to the proper FC level for SLAM and then continue to maintain it at those levels.
 
  • Like
Reactions: Newdude
You mentioned ordering the chlorine. When possible you want to go to the store to verify it's fresh supply. Chlorine breaks down and you want 3 months old or less. When you order it may be last years leftover stock they grab, because they don't know/care. Even checking it yourself, sometimes you have to dig deep on the shelf past the old stock.

 
You mentioned ordering the chlorine. When possible you want to go to the store to verify it's fresh supply. Chlorine breaks down and you want 3 months old or less. When you order it may be last years leftover stock they grab, because they don't know/care. Even checking it yourself, sometimes you have to dig deep on the shelf past the old stock.

The LC was delivered, but I don’t see anything on the bottles that indicate an expiration or package date. There are some random numbers and letters that look like a code, but nothing that stands out as a date.
 
  • Like
Reactions: ugadawgs311
Update: I waited until dusk to add 1 pound LC. I tested the chemicals earlier in the day with a test strip (still waiting on the new test kit), and all levels looked ok except TA was low, and CYA was very low (almost 0). Pump is running 24/7. I also ran my robot vaccum to suck up and at least “brush” some of the algae.

I’ll see tomorrow morning if the LC helps at all (although forecasted rain tomorrow may not help). Thanks again for all the tips and advice!
 
You’ve gotten great advice here and are on the right track to getting your water cleared up.

I wanted to ask, how do you normally chlorinate your pool?

You have a big pool, and live in a hot & sunny state.
PoolMath tells me that a gallon of 10% in a pool your size adds about 4.3ppm of FC. In the Summer, you can expect to lose about 3-4ppm per day to the sun. That means you’ll need to add close to a gallon every day, which may get expensive.

You may want to start thinking about a SWG (saltwater chlorine generator). I think it would be a lot more economical for you in the long run, after you get your water cleared up of course!
 
  • Like
Reactions: Newdude
You’ve gotten great advice here and are on the right track to getting your water cleared up.

I wanted to ask, how do you normally chlorinate your pool?

You have a big pool, and live in a hot & sunny state.
PoolMath tells me that a gallon of 10% in a pool your size adds about 4.3ppm of FC. In the Summer, you can expect to lose about 3-4ppm per day to the sun. That means you’ll need to add close to a gallon every day, which may get expensive.

You may want to start thinking about a SWG (saltwater chlorine generator). I think it would be a lot more economical for you in the long run, after you get your water cleared up of course!
Wow! I don’t think I’ve ever looked at it that way. I’ve been thinking about getting a SWG for the past 2 years, so maybe now is the time to go for it. My pool also gets blasted by sunlight in the summer - almost full sun from 9:30 am until 7:30 pm give or take. Economically, I think the SWG will pay for itself rather quickly.

Previously, I’ve just been adding chlorine weekly and more often during heavy use. Every year I usually have a battle with algae, green water, hazy/cloudy water, etc. about 3 or 4 times. I must admit, it’s been very difficult and frustrating to find a consistent process that continually works. Hopefully this SLAM process will help. And I honestly might look into a SWG tomorrow ha.
 

Enjoying this content?

Support TFP with a donation.

Give Support
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.