Pink "Stuff"

[djg9100]

First time in 18 years have a small amount of pink growth in a few places in corners and walls. 30,000 gunite pool that is due for resurfacing. Read that this is a bacteria an not algae. Chlorine pool.Calcium Hypochlorite. Trichlor tabs.

What is best solution for this?

Thanks

[PoolDoc]

What is best solution for this?

1. PH in a non-damaging range ( 7 - 8 ).

2. Chlorine ppm = 20% of CYA (stabilizer) level or more. (ie, if your CYA = 70, your chlorine should be 14 or HIGHER!)

3. Brushing.

4. Once you've got things under control low phosphates (<150 ppm) and high borates (> 60 ppm) will help prevent recurrences. But they ONLY help. You've still got to manage the chlorine and cya levels. But with a rough pool finish, managing these two levels well help, and shouldn't be hard or expensive unless your pool leaks.


So:

+ Read http://pool9.net/cl-cya/
+ Order a K2006 test kit. http://pool9.net//
+ Meanwhile, get a CYA test result, and dose with PLAIN 8% househould bleach as needed. On a 30k gallon pool, each gallon of 8% bleach will add about 3 ppm of chlorine.

[djg9100]

Thanks for the info. Got BBB info and ordered test kit. Also using phos-free weekly. Phosphates typically 100 or less.
Thanks and will advise of test results once I get the kit.

Don

[PoolDoc]

This product
CLOROX Pool Phosphate Remover 1 Quart removes 2,000 ppb (2 ppm) of PO4 from 10,000 gallons. That's usually less than 1/2 what Phos-free does costs, per unit of phosphate removed. It seems to be slow acting, so if you test immediately, you won't see much reduction.


WRONG: Turns out the Clorox phosphate remover is a seriously bad deal. A quart of the Kem-Tek predecessor product was labeled as removing 2 ppm PO4 from 10K gallons; the Clorox product is virtually the same price, but only removes 0.75 ppm from 10K gallons.

That means the Clorox product is actually 267% more expensive!


The Orenda PR-10000 product removes 5x that (10 ppm per 10k gal) per quart, so if you purchase it for less than $70/quart it's even cheaper. But you have to be careful with it, or it will cloud your pool.

[djg9100]

Ok. Got test kit and tested CYA. Based on the test my CYA is about 130. The black dot disappeared and the water level is below the letters CYA on the test bottle and based on scale it appears to be in the 130-150 range.

FC = 2.4 [12 drops x .2]
CC = 0.40 [2 drops x .2]

Additional tests
ph = 7.4
ALK = 170
Ch = 460

.

[PoolDoc]

You need to take your chlorine level to 30 ppm (20% of your CYA level). You can still swim with chlorine at 20%; I have a 200,000 gal country club pool that's been doing just that for the last couple of days -- no complaints, no problem, no one even notices.

[Watermom]

I wouldn't use any more cal-hypo. Your CH is getting too high. Just use bleach. (Plain, unscented generic Walmart 8.25% bleach is fine.)

If one scoop of the DPD powder turns the sample pink, no need to use a second scoop. Also, to make your testing reagents last longer, just use a 10mL sample of water and multiply the drop count by 0.5 instead of 0.2. Especially since you are going to have to run such high chlorine levels, you're going to go through the reagents fast. You can also use a 5mL sample, and multiply the drop count by 1. That would make them last even longer.

[djg9100]

Thanks for all the info. Would it be best to drain off some water to lower the CYA to 30-60 as per the pool builder instructions. Their initial instructions state that "adjustment to alkalinity or partial drainage of pool may be required should stabilizer exceed 60." Tonight's test results: CYA 125, FC 5.0, CC .04, PH 7.4, TA 150, CH 450 with a saturation index of .40. If it matters, the pool is 18 yrs old and it is time to redo the marcite. A friend of mine who has maintained pools for decades at his motels, said he paints them instead of re-plaster. Any thoughts on this.

Thanks again for your help.

[PoolDoc]

Lowering the CYA won't help you get rid of the pink algae; you'll still have to run 20+% chlorine level, just readjusted to whatever the new CYA level is.

Lowering phosphates (<0.100 ppm) and raising borates (>60 ppm) will probably help you get rid of the pink algae, and will definitely make it easier to avoid other forms of algae (green, mustard, black). Given that porous marcite is particularly prone to both mustard and black algae, that might be good idea.

Painting? I wouldn't if you can wait for the marcite. Ask your friend how often he repaints pools . . . and make sure you want to get on that treadmill before you do so. Keep in mind that painting makes resurfacing considerably more difficult, since every trace of the paint has to be removed.

[djg9100]

Yes, great idea. I really don't want to have the high chlorine and based on my other posts it seems like I need to take out some water and replace.