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View Full Version : What should Calcium Hardness be?



troykristoffer
05-30-2007, 10:45 PM
I have a gunite 28,000 gallon pool which is completely cloudy after being shocked and I cannot see the bottom of the shallow end. All of the algae is gone (well theres no green in the pool whatsoever. Currently working on getting rid of any residual dead algae.)

I know this can be caused by either all the dead algae, which I'm working on right now.

I also know this could be from high calcium hardness... but I dont know what it should be.

I did the chemistry test with a Leslies drop based test (25ml of pool water, add 10 drops clear and mix, ad 5 blue and it turns red, add single drops of something else until it turns blue.) It took 12 drops for it to turn blue, and it says to multiply that by 4 = 48.

SO thats my calcium hardness supposedly, but I don't know if its normal or not, and an hour searching the forums resulted in no definite answer for me :(

Also, what else could the cloudiness be. I've backwashed, cleaned the filter manually, and have been running my filter for almost 5 days straight.

I suspect its dead algae, and will know more in the morning I suppose. I put a nylon stocking over my skimmer basket and it got caked with some slimy whitish-brown stuff every few hours. The calcium test was just to see.

Sumo1
05-30-2007, 11:25 PM
Welcome! CH for a gunite pool should be between 200-400ppm so I suspect there's an issue with the way you're testing. I'm sure one or two of the more experienced folks will be along soon to straighten it out. Since this is your first pool season, you've come to the right place. ;)
Hal

chem geek
05-30-2007, 11:49 PM
I don't know about the Leslie's test, but I thought it was the same as the Taylor K-2006 which has these instructions (http://www.taylortechnologies.com/products_instructions.asp?Type=Number&Number=5811). It says to multiply the number of drops by 10 if using the 25 ml sample and to multiply the number of drops by 25 if using the 10 ml sample. So if you used a 25 ml sample, then you would have 120 ppm CH which is still low, but sounds more accurate.

To clear the dead algae you need to keep the chlorine levels high (you didn't give your CYA level, but use the "shock" column in this table (http://www.poolforum.com/pf2/showthread.php?t=365) as a guide) and should use a skimmer sock (or nylon stocking as you are doing) and vacuum to waste from the bottom of the pool (for settled algae), and brush the sides to help get the algae to the bottom or into the skimmer or filter. You'll need to clean your filter at some point as well. Most important of all is to have patience. See this link (http://www.poolforum.com/pf2/showthread.php?t=1180) for how a pool WILL clear from algae using chlorine alone. Keep the chlorine at shock level until 1) the Free Chlorine level holds overnight and 2) the Combined Chlorine is close to zero (< 0.5 ppm) and 3) the water is clear.

Richard