total and free chlorine

[pup55]

I keep having problems with algae growth and would like to know if the total and free chlorine are to high could this be a cause? My total and fre are both at 10 and I cannot seem to get it lower.I have an off line feeder and I keep adjusting it and they both stay at 10. Could this be the cause of the algae growth?

[chem geek]

Read the Pool School and get yourself a good test kit -- either the Taylor K-2006 you can get at a good online price here or the TF100 kit from tftestkits.net here with the latter kit having 36% more volume of reagents so is less expensive per test. Since you have an a chlorine feeder that probably uses Trichlor pucks/tabs, your Cyanuric Acid (CYA) level may be very high and that makes chlorine less effective allowing algae to grow faster than chlorine can kill it. See Defeating Algae in the link I gave to the Pool School.

[pup55]

Thanks for your response. My cyanuric acid is at 30-50 right now.

[chem geek]

Shock the pool with 20 ppm FC. How sure are you that the CYA is 30-50 ppm? Test strips and pool store results are notoriously inaccurate for CYA. If you use Trichlor pucks in an offline feeder (what does that mean "offline" -- usually it's referred to as an inline chlorinator), then unless you've got a small pool with a short season and a sand filter backwashed weekly or have lots of rain overflow, then the CYA is likely higher. For every 10 ppm FC added by Trichlor, it also increases CYA by 6 ppm. Even with a low daily FC usage of 1 ppm, the CYA added by Trichlor would be over 100 ppm in 6 months if there were no water dilution.

[pup55]

I am using test strips with a sand filter and I do backwash weekly with 28,000 gallons. I am going to purchase a new test kit and recheck the cya.

[pup55]

Update, came home from work and pool has algae growing again.
TH 100
TC 10
FC 10
PH 6.2
TA 80/120
CA below 0

I just scrubed the pool to get rid of all the Algae and will shock it tonight. I have had the pool for 9 years and haven't changed anything it the algae keeps coming back. I also have another issue. You can smell the chlorine in the pool and anytime I add any type of powdered chemical the pool turns cloudy right away and will not clean up for a good week.HELP!!!!!!!!!!!!!! I am using 2 different types of test strips and I am going out to by a test kit this week.

[chem geek]

Two days ago you said your CYA was 30-50 and now you say it's "below 0" (it can only get to zero, not below). With a proper test kit, you'll be able to know what is really going on.

If you are adding Cal-Hypo and it remains cloudy, then your Calcium Hardness (CH) may be high. If you use chlorinating liquid or 6% unscented bleach, then this won't add either CYA nor CH. Please read Defeating Algae in the Pool School link I sent to you. The key is to maintain a sustained high level of chlorine in the pool to kill algae and then after it is killed and the water is clear then maintaining a proper FC/CYA level will keep the algae away.

[pup55]

I am having a really tough time matching the colors up on the test strip. When I get the new test kit it should be better. Thanks for your help, it sounds like i am starting to bother you. again thanks for your help.

[czechmate]

Look at the number of Chemgeek postings.
If he ever felt bothered he would have stopped after 1000 replies.
I think that 5 drops on a liquid are much better ways of testing and more economical than strips.
Keep them inside the house though to retain the proper results.

[Me...]

I am starting to really like these, the Pro 7 kit in particular. Saves deciphering colors.

http://www.lamotte.com/pool_spa_water/p ... _kits.html

[chem geek]

There's more info on the ColorQ here. Note that the chlorine test is based on DPD so will bleach out (and be inaccurate) at higher chlorine levels, starting to have problems above 5 ppm and not being able to properly register 10+ ppm. The pH test will be sensitive to high chlorine levels, but that's true of virtually all test kits. The other tests can be OK -- CH is off more than a drop test, but CH levels are higher anyway so on a percentage basis it's not bad. CYA seems OK.

pup55, I'm not annoyed. I was pointing out inconsistencies to emphasize the importance of having a good test kit. The Defeating Algae link emphasizes the importance of maintaining a high chlorine level during the shocking process. It's more detailed than I would rather type in each post which is why I refer to it.

Richard

[pup55]

I undersatand, you must type this stuff all day. I did print out all the information that you gave me an will work on the pool as soon as I can pick up the test kit. I have 2 different test strips right now and sometimes it is so difficult to try and match the colors up.
Thanks for all your help
Steve

[pup55]

Guys I continue to work on my pool to get rid of the algae. I thought I was doing well till I looked at the pool and the algae was back. I still need to pick up a good test kit and right now I am using 2 different test strips. I tested it today and this is what i have. I shocked the pool about 2 weeks ago and thought it was good.
TH 100
TC 10
FC 10
PH 6.8/7.2
Alk 100
CYA 30-50
I have tried everthing to get my TH and TC down but no matter what I do they stay the same. I have read most of the information on this site and I dont see anything on TH and TC being so high and what cause's this? Do these numbers being so high tell me something about whats wrong with my pool. Do these numbers being so high mean that the chlorine is not sanitizing my pool?

[Denali]

Guys I continue to work on my pool to get rid of the algae. I thought I was doing well till I looked at the pool and the algae was back. I still need to pick up a good test kit and right now I am using 2 different test strips. I tested it today and this is what i have. I shocked the pool about 2 weeks ago and thought it was good.
TH 100
TC 10
FC 10
PH 6.8/7.2
Alk 100
CYA 30-50
I have tried everthing to get my TH and TC down but no matter what I do they stay the same. I have read most of the information on this site and I dont see anything on TH and TC being so high and what cause's this? Do these numbers being so high tell me something about whats wrong with my pool. Do these numbers being so high mean that the chlorine is not sanitizing my pool?

Hi,

As chemgeek said test strips aren't real accurate. An example is your pH reading. 7.2 would be an OK level whereas 6.8 would be low.

If you have algae starting up you don't want to lower your chlorine level. If anything you'd want to raise it and keep it up until the algae was gone.

As for the TH of 100, if that is hardness you don't need to lower it.

Once you have a good test kit then you can be confident in your numbers and you can get solid advice on what needs doing.

[pup55]

I will be getting a test kit but if my TC and FC are both at 10 would that not kill the algae? I see that most of the people on this site have there TC at 3 and FC at 1.