Cloudy water after floculant use

[robhawaii]

I have a Coleman above ground 18 foot x 48 inch pool that I added floculant to.  I let it sit for a day and a half and the water cleared except for the green algae that had settled to the bottom of the pool.  I carefully and slowly vacuumed to waste.  I was able to vacuum 90 pct of the settled matter, but during vacuuming I stirred up some of this.  I then ran the filter (just changed sand last week) for 6 hours and water is still cloudy and light green.  I let it sit without the filter running overnight and it appears that there was some settling of the matter to the bottom, but I can't see the vacuum head at the end of the aluminum pole that is in the pool.  This makes it difficult to vacuum again.  Should I just do another floculant treatment?

Thanks

[Cusser]

I have a 15 ft above ground pool.  If I get a lot of crap on the bottom, I vacuum to WASTE, not through the filter.  I can do such pool quickly and then top off with water.  I wouldn't be surprised if small stuff goes right through your filter, so doesn't all get backwashed out.

[robhawaii]

Actually I did vacuum to the waste setting.  Then after vacuuming I set to filter setting.  Water cleared a little after a couple of days but not enough.   I'm doing another floculant treatment and need to let it sit another 12 hours.  Hope this works.  

[waterbear]

You need to kil the algae first before adding floc. Post a full set of test results so we can help you with that. I assume you are using trichlor tabs for chlorination. Do you know your CYA level? If you are using trichlor or dichlor there is a good chance the pool is overstabilized which is why you have algae. Once we have the test results I can advise you better.

[robhawaii]

Thanks for the advice.   Yes I am using Trichlor tabs for chlorine. (Pool Time brand). CYA was in normal range when checked before I added second Floc treatment.   Once I vacuum the settled Floc and run filter for a cycle I will check chemistry and report back.  

[waterbear]

4 hours ago, robhawaii said:

CYA was in normal range

That tells us nothing. Numbers do. Normal range for a manually chlorinated pool is 30 to 50 ppm and at that level of CYA you need to maintain a FC of 4 to 6 ppm and shock to 15 to 20 ppm. If the CYA is higher then the FC and shock values need to be higher also to maintain the same level of chlorine activity. GThe numbers above is the same chlorine activity in a pool with NO CYA, FC 1-3 ppm, and shock to 10 to 12 ppm. Since you are dealing with algae it's pretty certain that you are not maintaining proper FC levels for your CYA, which is pretty common when using trichlor, especially in areas that have an extended (more than 2 or 3 month) swim season and do not winterize pools, like Florida where I live and LA where your IP says you are located.

You cannot filter out living algae or floc it out. It must be dead (turned white) first. If you maintain the proper FC/CYA ratio you will not get algae, and if your CC is never over .5 ppm then you don't need to shock.tr

FWIW, for every 10 ppm FC added by trichlor you are also adding 6 ppm CYA so your CYA will always rise when using triclor. Dichlor is worse, it adds 9 ppm CYA for every 10 ppm FC added. The only way to lower CYA is by draining some of the water and refilling. With a vinyl pool this means never lowering it more than a foot below the skimmer before refilling.the

To kill algae you need to bring your FC to the shock level for your CYA and KEEP IT THERE, with the pool circulating, until the algae has all turned white. With a vinyl liner pool you have the second problem that vinyl pools should not be shocked to more than 15 ppm to prevent damage to the liner. In that case the use of a polyquat 60 algacide is the best way to go. Stay away from linear quats unless you want a lot of foaming and stay away form copper based algacides unless you want to risk staining your liner and staining hair green. Sodium bromide based algacides temporarily convert your pool to a bromine pool which takes the CYA out of the equation and kills the algae but UV converted it back to a chlorine pool and the CYA comes back into play and the algae usually returns unless you do the drain and refill dance to lower your CYA.

[robhawaii]

Thank you for this very detailed explanation and recommendation's.  If I follow this I might be able to solve my recurring algae issues.

Actually, I'm on Hawaii island in Upper Puna on the East side at 1200 ft elevation.  Our home is in a dense forrest/jungle in lava zone 3.  Between May-December daytime temp is 78-80 and nights 68-70.  January-April is low 70s in the day and 59-63 at night.  The pool is warm enough to enjoy (78-81) between May-December if it is sunny and covered overnight.  Our average annual rainfall is 140 inches and tends to be acidic.

I'm including a photo of the test strip from this morning after vacuuming the floc yesterday afternoon.  I read Tot Chlor = 1, FC=0,PH= 7.8, Tot Alk=120, CYA=100.   However, I normally have low PH and low Tot Alk and add baking soda to raise.  CYA and FC also tends to be low. I will admit that I tend to focus on correcting Tot Chlor and PH and overlook the FC and CYA, my bad.  I appreciate the education on this.  My usual low FC and low CYA is likely causing the algae as you stated!

BTW - Our water is rainwater catchment in a 10K gallon galvanized tank with food grade liner.  Water is filtered to 5 microns and run through a UV sterilizer before it enters our home.  Since rain is on the acidic side we have a reverse osmosis that also adds minerals and balances PH for our drinking water.   Just wanted to add this info since I mentioned that we have 140 inches annual rainfall and it's acidic. 

Thanks again! 

 

[waterbear]

Strips are basically useless. While they are precise (repeated tests on the same sample give the same results, they are not really accurate for many of the tests (giving results that indicate the actual water parameter levels of the sample). also the precision of strips is often too wide to give any meaningful info to balance water. Case in point, TA scale is +/- 40 ppm or worse  and the pH scale has big jumps of .6. TA should be adjusted to 50 to 70 ppm for best pH stability and pH needs to be monitored more closely. There is a big difference of pH of 7.2 and 7.8 in terms of water balance and with a vinyl pool a pH of below 6.8 to 7.0 will damage your liner. They CYA test in strips is another one that is basically useless.

My suggestion is to invest in a Taylor Technologies K-2006 (FAS-DPD testing method for chlorine) kit and stop using strips. It is worth every penny.

https://www.taylortechnologies.com/en/page/231/k-2006-complete-kit-with-fas-dpd

Also, read these:

https://www.poolspaforum.com/forum/index.php?/topic/52523-some-truths-about-ph-and-ta/

https://www.poolspaforum.com/forum/index.php?/topic/28846-lowering-total-alkalinity-howto/

https://www.poolspaforum.com/forum/index.php?/topic/58991-false-high-ph-readings-when-shocking-some-truths/

https://www.poolspaforum.com/forum/index.php?/topic/53108-some-truths-on-bleach-dosing/

You might want to consider switching to liquid chlorine or laundry bleach (sodium hypochlorite) for chlorination once your CYA reaches 50 ppm with the trichlor and stop the trichlor. Cal hypo (calcium hypochlorite) is also an option for chlorination since your fill water is so soft. Just remember to predissolve it in a bucket of water before  adding so you don't bleach your liner. It is very slow dissolving and if added directly to the water will sink and sit on the liner and cause bleach spots. Maintain your FC at 4 to 6 ppm and if your CC never rises above .5 ppm you do not need to shock.  Use bleach or cal hypo to shock if/when needed 

[robhawaii]

This is all great information.  If the measured measured levels are not accurate using strips it's just a waste of money and time to be adding chemicals and then it does not solve the issue(s).  The included links for correcting levels is also super helpful.  Thank you!

[waterbear]

3 hours ago, robhawaii said:

If the measured measured levels are not accurate using strips it's just a waste of money and time to be adding chemicals and then it does not solve the issue(s)

Pretty much! (But it does help the pool/spa supply stores and chemicals manufacturers and distributors bottom lines!)