Green pool with clogged sand filter after 2 weeks out of town

[jtran69]

Sorry about writing on http://www.poolforum.com/pf2/showthread.php/25463-Help-with-sizing-new-filter/page2

Pump is working normal again after more backwash and rinse. Water looked much better then Sunday's night as in less green. Here's the brief history.

Sunday night: Added 1 gallon of bleach, 4 cups of dichloro out of panic since pump was not working properly.
Monday night: added 1/2 gallon of bleach and scrubbed the pool.
Tuesday night: added 1 gallon of bleach, cleaned the sand filter and pump began to work.
Tonight: plan to figure out how to disable the copper block or remove it and follow up with the expert advise.

Here's my measurement this morning, Wednesday.
FC=0.5ppm
CC=0.20ppm
PH<7.0 so I added 22 drops of R006 for the color to match 7.0
TA=30ppm
CA>100ppm

[jtran69]

I can see the bottom of the pool now since the water is not as cloudy and most of the green algaes are gone.
Adding to my log for Wed night, I added a gallon of bleach and 4 cups of borax.

Please advise on the best way to have balance water.

[CarlD]

Why would you add R-0006 to the pH test? If you did the test correctly and your pH was below 7.0, adding Borax was the correct step.
Did you run the CYA/Stabilizer step? I assume by CA you mean Calcium Hardness, not Stabilizer, but if it is stabilizer, then you should ONLY use bleach in your pool, and use enough to raise your FC to 25ppm. If it is the Calcium measure then you need the CYA measure so we can determine the level of shocking you need. In the meantime, you should add at least 154 ounces of 8.25% bleach and get your FC up to at least 12ppm, and keep adding bleach to keep it there, assuming you have little or no CYA.

If the "HTH 6-way stick" is a chlorine tablet, stop using it. Use only bleach. If it's test strips, stop using them, too.

Need that CYA number and a good, current pH measure.

[jtran69]

Wednesday night, I added 128 oz of bleach.

Here's my pool chem number for this morning.
FC=3.0
CC=0.5
PH<7
TA=40
CH=220
CYA>>100

Then I added 3 cups of Borax which I need to buy more afterwork.

Tonight, I plan to add 154 ounces of bleach follow more of your expert advises.

[CarlD]

OK. You are going to need to double that amount and get your FC to 25ppm, and keep it there, now that I know that CYA > 100. Don't worry about TA or CH, but get your pH up over 7, first.

[jtran69]

Is 5 cups of borax every night til pH=>7?

[FormerBromineUser]

If you have time, you can slowly add the borax to skimmer, wait around 2 hours, and then retest PH. Add more borax as needed. You need to get that pH above 7 as soon as you can.

[jtran69]

Thursday night I added 2 gallons of bleach and 1 box of borax; PH was not quite 7.0 but more likely 6.9.
Then I added 4 more cups of borax.

Friday 11am, PH=7.2, FC=10.5.
Then I added 3 cups of borax and went to work.
Water is looking better now but seeing some black/gray dirt on the bottom -- another round of vac should remove them.

Friday night plan, please advise.

[FormerBromineUser]

Get your FC up to 25 ppm tonight. Retest 1 hour later to make sure you hit that target. If not, add more bleach. If you have time over the weekend, maintain FC at 25 by testing and adding bleach at least 3 times per day. Some people only recommend 3x/day but I think a 4th would only help if you have time. And no more Di-Chlor panicking!

[jtran69]

At 8pm, pH=7.6. I added 2 gallons of bleach.
At 9:30pm, FC=18. I added 1 gallon of bleach.
At 11:30pm, FC=25. Yes yes yes!

[SunnyOptimism]

You need an accurate CYA measurement in order to know where you are at so you can target your FC properly. Please do a dilution test - mix 1 part pool water with 1 part bottled or distilled water and then redo your CYA test as normal. Take the results of that test and multiply by 2 to get a correct CYA value.

[jtran69]

5:30pm, FC=15, pH=7.5. I added 1 gallon of bleach.
I have about 10 ml of R0013 left for one cya mea and will take it when FC is back to 25.

[SunnyOptimism]

You can get 2oz refills and even huge 16oz bottles on Amazon. I have a 2oz bottle that I'm about 1/3rd the way through (16oz is kind of crazy big for a residential pool user).

Good luck and I'll keep an eye out for your CYA result. My fear is that your CYA is crazy high and 25ppm FC may not be adequate for a shock level. Also, when your pool is clear, knowing that CYA exactly will help you target a proper FC keep the algae at bay. If it's really high, your pool may warrant some water draining to help get your CYA down...not fun to dump water but the alternative for an over-stabilized pool is to run at a higher FC level which means more bleach and more frequent bleach additions which can be costly too in the long run.

First things first, get the pool sparkly again, then worry about stabilizer....

[jtran69]

I've done a vac earlier and the water is looking really good now. My kids kept asking if the water is ready yet since its has been 90+ over the last 2 days.

[FormerBromineUser]

Geez! High of 45 today here. Brrr! Let the kids swim! FC of 25 won't hurt them, just have them wear regular old swimsuits. Sorry, didn't realize you were keeping them out of the pool. As long as you have good levels of sanitizer and the water is clear enough to see, swim! As far as I know, algae in a clear, sanitized pool never hurt anybody. Take a dunk for me, sitting here in sweats, sweatshirt, fleece jacket ... and I'm INDOORS!!!

[FormerBromineUser]

I should also add that your pH is now okay to swim in. Your less than 7 pH was not.

[CarlD]

Getting cooler fast here now that it is October...

[Watermom]

but the alternative for an over-stabilized pool is to run at a higher FC level which means more bleach and more frequent bleach additions which can be costly too in the long run.

Actually, pools with a higher CYA usually can get by with less frequent dosing with bleach. Some people deliberately keep their CYA on the high side for this very reason.

[SunnyOptimism]

Actually, pools with a higher CYA usually can get by with less frequent dosing with bleach. Some people deliberately keep their CYA on the high side for this very reason.

Thanks, @Watermon.

I think it all depends on what is viewed as "high" and what set point you use for FC/CYA ratio. I try to follow the 7-11 formula for FC -> min FC level is 7% of CYA with daily target FC level of 11% of CYA.

Once you get much above 100ppm CYA, the 7-11 rule becomes much harder to maintain as my understanding is FC loss rate is not constant but proportional to FC concentration. So, at a higher FC level, you tend to lose FC at a faster rate than at a lower level. That was my point about more frequent additions.

Also, shocking your pool starts to become impractical at CYA levels above 150ppm as the amount of FC needed is quite high. I wouldn't go so far as to say you'll damage anything, but it will be a significant amount of chlorine to add and maintain. At some point, you reach a breakpoint where the cost of all the bleach you'd have to add (and time spent trying to maintain it and measure it) is probably as costly as just dumping half the water and starting with a lower overall CYA.

I'm not arguing against your point as I maintained my pool for quite sometime with my CYA at 90-100ppm, but I have the luxury of an SWCG and don't have to do any jug dumping.

[FormerBromineUser]

Jtran: What's happening?

Rest: Ben, Richard, Lisa?

[jtran69]

Sunday night at 11 p.m..
fc= 15, cya =190. I added 1/3 gallon of bleach.

[SunnyOptimism]

@jtran69,

I see you're in northern CA, are you able to drain and refill or are you still in water restrictions?

A CYA of 190ppm is really very high. During "normal" operation you'd need to maintain a minimum FC level of 14.2 just to keep algae at bay and your daily target level would have to be up around 20ppm somewhere just to ensure enough reserve disinfecting power. Dumping half your water and replacing would bring you back down to 95ppm CYA which would still be high but much more manageable from an FC perspective.

That's just my opinion. I had water that got up to 150ppm CYA and I gave up trying to fight that and just dumped half my water. Since then it's been a lot easier keeping my pool water balanced.

[jtran69]

We have to ration water and the yards on our street are mostly brown -- also washing your car is not allowed. I'm thinking to about fighting this hi cya til the end of the month and close the pool for the season.
I'm adding half gallon of bleach every night.

[CarlD]

Sunday night at 11 p.m..
fc= 15, cya =190. I added 1/3 gallon of bleach.
Are you still fighting algae or is your pool clear?
If it is clear, you can maintain your fc about where it is till you close. If it is not you still have to shock up to 25-30 to clear it, and should do so before you close.

The only benefit to closing with algae is over the next several months an algae infested pool will consume CYA, but you will have a huge mess to clean up, taking lots of chlorine. But if you cannot drain and refill because of water restrictions, your choices are limited to a high CYA pool, or an algae "science project".

[SunnyOptimism]

One other option, and it ain't cheap, is reverse osmosis (RO) filtration. I know there's at least one company in southern CA doing it so there might be one up in your neck of the woods.

RO will remove almost everything from your water - calcium, salt (measured by TDS), CYA, Carbonates, borates, metals, etc. I'm not sure if companies will RO with algae present or not. You typically have to let your FC drop to zero (FC destroys the RO membrane material) and they filter and rebalance the water for you. The recovery fraction for an efficient, industrial RO system is approximately 80% so you would still need to add some fill water.

Last time I looked into it here in southern AZ, it was about 2X the cost of water replacement.

[CarlD]

What little I know about RO is that it is primarily a de-salinization tool. At one time many cruise ships augmented their fresh water with RO, but could only run it at sea, not in port. Sewage and heavy metals in river run-off prevented usage.
I don't know how much has changed with the RO technology since then.

I thin I remember Ben had looked into a chemical that could clear cyanuric acid, but I forgot what it was, how successful it was, or how expensive and involved a process.

[SunnyOptimism]

See for example - http://poolservicestech.com/tag/reverse-osmosis/

RO is a boom-bust business. When water is cheap to replace, it can't compete. However, with recent price increases here in municipal water rates, RO is starting to come on par with water replacement. As long as the company you choose uses industrial grade equipment (not the under-the-sink garbage you get at HomeDepot), 80% recovery is very achievable. It's all dependent on the water pumps and pressure you use, the higher the pressure, the better the efficiency. Typical filter membrane pressure is anywhere from 250-300psi. Normally these companies have to back a truck up into your yard and the process can take a couple of days depending on water volume. High pressure, industrial units typically process a few thousand gallons per day. Desalination typically requires several filter units cascaded together as a single RO membrane can only fractionally change the salt level.

Yikes! A chemical that eats CYA?!? Not sure I want that in my pool :p

[CarlD]

Portable and even hand-pumped RO units for desalinization to make drinking water have been available for boaters/yachtsmen for well over 20 years. They are very pricey, though.

[FormerBromineUser]

Jtran, I thought you were maintaining a FC level of 25. Not?

[CarlD]

Keep that FC up, but do NOT use Di-chlor powder or Tri-Chlor tablets, and certainly not the HTH sticks. Stick to bleach or liquid chlorine. With your CYA that high, once you kill the algae, you'll be able to maintain a residual FC level easily, probably best to keep it close to 15, and won't have to add much bleach at that point.

If your CYA is really that high, you can safely bring your shock level to 30 or 35ppm without damage to your pool.

[FormerBromineUser]

How are things?