Hth 6way tester plus help to get rid of algae

[AridZone]

I have been having problem with algae growth in my pool. Over a period of 2-3weeks I have been putting 10lbs of shock 2lbs at a time. The algae has almost all gone away.
They look like this. Seems to radiate from the auto cleaning nozzles.





I use test strips and every month I have Leslie test the water. I finally decide to get the hth 6way tester at Walmart.
The results I got was this.
CYA=60-70
PH=7.8
Alkaline=100

Now for Total Chlorine the color was redish. Like this.


Does that mean it is off the scale ? Must be because of the 10lbs of shock.

I also have 2 types of test strip and they show Free Chlorine to be at least 10.


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fAs for the hardness it must be also above the scale as I could not get it to change color. I stop after about 40 drops (or 400ppm). Last test by Leslie a month ago was 400.

I am confuse as I still see some new algae growth this morning despite such high Free Chlorine ? For the past several days I am only running the chlorinator for new chlorine. Am I doing something wrong ?

Thanks for any help.

[PoolDoc]

Hi Arid;

Sorry it's taken me so long to reply. I enhanced the contrast on your first photos a bit - I don't thing that's algae. I'd bet on it either being iron OR some discoloration of any organic binders in the finish. You can test, this way:

1. Turn off your pool pump.

2. Take either some chlorine powder OR a piece of a chlorine tablet, and put it on one of the brown 'algae' marks.

3. On the OPPOSITE side of the return, put a handful of Vitamin C tablets on another mark. Make sure the tablets are clustered together -- chlorine destroys vitamin C, so you want enough tablets piled up, so that the vitamin C on the bottom of the pile is not destroyed.

4. Wait 1/2 hour, and then remove the tablets or powder. (If they've dissolved or are just a powder, you can just sweep what's left out into the pool.

5. Check the spots underneath.
(a) If it's algae, the spot under the chlorine should be clear, but there will be little or no effect under the vitamin C.
(b) If it's iron, the spot under the Vitamin C should be lighter, but the spot under the chlorine will probably show no effect.
(c) If it's organic + chlorine, then the spot under the chlorine may be darker (or not) and the spot under the Vitamin C should be unaffected.

Regarding your calcium -- get some distilled water (distilled, NOT spring water or anything else). Wamart has it in gallon jugs, for about $1 in my area.
Great Value: Distilled Water, 1 Gal
Take a mixing cup and fill it 1/3 with pool water, and 2/3 with distilled water, making 1 cup. Mix, and then run your calcium test on THAT mixture. Multiple the result by THREE.

Very high calcium can complicate pool chemistry in a variety of ways.

Regarding your OTO result -- that is 'out of range' in the sense that it doesn't match any results on the color block. But it's not out of range for the OTO reagent -- that color corresponds approximately to chlorine in the 20 - 35 ppm range. That's a good level for clearing algae in a pool with CYA = 70 ppm. Read the "Best Guess" page linked in my signature for more information.

But, as I said, I doubt that your problem is algae.

[AridZone]

Thanks for your suggestions.

Yes, there is a good chance it is not algae.

Anyway whatever it was it has all gone away. I will definitely remember your tablet test if it ever comes back. I also redid the hardness test and it did finally turned blue. It about 800 to 900 ppm. I lost count after about 80 drops.

I also cleaned the cartridge filters as it was dued.

I just did the Total Chlorine test and it has started to come down and I can see yellowish color now. Its now just above 5. Free Chlorine using the test strip still show a high reading about 8.

Looks like my problem is the hardness. I need to bring that down.

[PoolDoc]

Looks like my problem is the hardness. I need to bring that down.

Don't fix what's not broken! If you have a pool heater, or are getting some scaling, then you may need to work on the hardness. Otherwise, not so much.

You have to realize that hardness is not that easy to remove -- you have to precipitate it and then filter or vacuum it out. You can drain and refill, but in Arizona, there's a good chance your fill water won't be a big improvement. You CAN use a modified version of a potable water treatment method called lime softening. But you want to be 100% sure it will work BEFORE you start on your pool.

This bucket test will give you those answers: http://www.poolforum.com/pf2/showthread.php?16992

Good luck!