Is it safe to swim in a pool that has algae in it?

Answer

The Algae won't hurt you. But if the chlorine isn't killing the algae, then other microorganisms might be present also. But then, we grew up swimming in ponds and streams. After shocking the pool, the algae will take longer to dissipate, so I'd let the kids in 24 hours after shocking, even if the water is green.  

Answer

No it is not!!!!!! We just returned from a trip to Mexico and stayed at a high end Resort. The pool was beautiful but on three of the days there we saw algae in the pool. It was cleaned out with manual sweeping and I suppose chlorinated or shocked. When we got home I had this horrible itching that was unbearable. Nothing could be seen on the skin, but it was so intense I could not not stand it even to sleep. The doctor prescribed a cortisone cream and said it had caused a severe dermatitis that may lie dormant and will be activated by heat, hot water, and WAS caused by the unsanitary conditions that let the bacteria and such grow in this pool. Do not swim in algae filled pools  

Answer

Is there a mycologist in the house???
Greetings! I read this letter and replies quite closely as Oregons Willamette valley gets hit with the worst algae outbreak in recent memory .
This is the first I've heard of algae causing dermatitis related problems. I remember coming out of streams and ponds covered with it down in S.C. Perhaps a strain that won't survive this far north?
Allergic reaction I could understand. But those are immuno-specific and tied to the patient, not the organism present in the pool.
But I am a lot more inclined to cast the questioning eye toward the sparkling water and filtration of the pool.  

Answer

The definitive answer is "it depends."
Europeans swim in pools that have algae on the walls, yet also have a high ORP (oxidation reduction potential- as measured in millivolts of conductivity).
The high ORP is usually due to the use of ozone, which kills viruses, bacteria and pathogens, and oxidizes bather waste (urea - sweat, urine & cosmetics - suntan lotion, hair gels, cream rinse, etc.). The short half life of the ozone does not allow the ozone to remain in the vessel (pool/spa) long enough to kill the algae. Thus their pools are sanitary & safe to swim in (no pathogens and sparkling clear), yet they have algae.
The reader who got sick probably swam in a pool which had bacteria, viruses, and algae due to poor water chemistry maintenance.
The best piece of advice that I can recommend... carry your own pool water test strips when you travel, and perform a test before swimming. I do this when ever I travel, and especially when using a public spa/hot tub.
2 rules to remember:

1. 1: If your eyes burn after swimming, it's not due to TOO MUCH chlorine, it's from too little (chlorimines). (Or improper pool water pH).
2. 2: If you smell "chlorine" when you approach the pool or spa, turn around & go golfing. What you smell are chloramines (chlorine that's combined with bather waste, aka. combined chlorine), and that is an indication that there is not enough chlorine in the pool!! A high level of chlorine in a pool (even as high as 10 ppm) barely has a smell. And yes 10 ppm is safe to swim in - only hyper-sensitive folks might itch and cheap fabrics may bleach/fade.

Remember: Most water chemistry problems, eye irritation complaints, and murky water are a result of too little chlorine!

 

Answer

If it's a public pool and it's green, I wouldn't dip my finger in it. If it's your private pool, then it depends, I am not going to repeat the valid points above..
If you are a pool owner and looking for a solution to the algae problem, please check out my web site www.poolbutlerswimsafe.com