Raising Chlorine Making Water Green

[Cookieman]

Been using BBB method for a few months successfully. Tree debris and pollen began to fall and I let chlorine level drop too low. There was no algae at that time. I noticed when I checked Cl level - DPD FAS method -Taylor 2006. I put 4.25 gal of bleach in - pool is 25k-26k gallons. The next day Cl was 0 and water was real green, with small white spots on surface of water, and some foaming in skimmer, but no algae on sides or steps that I could see. Did nothing else for 4-5 days while looking for information on this site. Thought maybe I may have to much chlorine and it wasn't registering. I then read in forum that is unlikely with DPD FAS method. Pump has been running 24/7 f0r last 3 weeks to keep pool clean. Green color actually improved with chlorine at 0, but this weekend a small amount of algae began to appear. I decided to continue to add chlorine to raise level to at least 10ppm. Numbers when I began on Friday 3/31/12: Cl - 0, PH- 7.6, Alkalinity-110, Calcium Hardness-80, Cyanuric-55. Began Saturday with 1.5 gal bleach at 1pm and Cl went to 1ppm. Added another 1.5 gal at 145pm, in 30 min Cl was at 3.5ppm. Checked Cl at 930pm and Cl was 2.5, so I added close to 3 more gal of bleach. Checked Cl this morning and was at 4.5. Green color gets worse as I add chlorine, and some foaming in skimmer. PH, Alkalinity have not moved. Added another 1.5 gal of bleach today after brushing and backwashing Hayward sand filter. I am now at 4.0PPM Cl. Do I coninue to add large amounts of bleach even though it seems to make green color worse? How much can I add at one time? Sorry so long, but wanted all information included.
Pool information: 18x36 vinyl pool; Super Pump, Hayward Sand Filter, Heater(valved off), county water system

[waterbear]

was it a clear green or a cloudy green?
the foaming makes me suspect an algae bloom but if the green got worse as the chlorine level went up that could be iron (which colors the water yellow so it looks green against the blue liner) or copper (which colors the water green from the getgo).

My gut level feeling is that you have a algae bloom that that is what is making the water green but a full set of test results would be a good starting place. When you report chlorine readings it would help a lot if you report both FC anc CC since that will tell us what we need to know. I susepct that you have been reporting FC readings and that the CC readings have been much higher.

Algae will not always be on the sides of the pool. Green water is often caused by the free floating algae in the water.

[BigDave]

I can't venture a guess why it looks greener but with a CYA of 55, Ben's Best Buess Chart shows that you need to raise your FC to 15-20 and keep it there to fight the algae. Trouble is, if you don't hit it hard enough you're wasting your time (and chlorine). More Bleach!

The plan for fighting algae is:
Raise FC to shock (per Best Guess Chart) and keep it there.
Test FC and correct as often as you can.
Run pump / filter 24x7 and clean filter as necessary.
When you hold FC overnight and have less than .5 ppm CC, you have won, let the FC drift back down.
Apply POPP (Pool Owner Patience and Persistence) liberally.

PS Waterbear and I were posting at the same time. He may be onto something regarding metals and you do need to be specific about the readings being FC CC or TC. But I think he and I agree you likely have an algae bloom and that's what this plan aims to fix.

[Cookieman]

Since I began to notice some algae collecting in certain spots late in the week, I tend to agree with you and Waterbear on the algae bloom. If I can believe pool stores, I've never had an issue with iron before. I am not on well water. By my math I caluclate for 26000 gal, I need to add 1 gal of chlorine to increase 1ppm. Does that sound right? Is there a limit to how much I can add at one time? Thanks for the help

[BigDave]

According to ThePoolCalculator, adding 1 gallon of 6% bleach should increase your FC by 2.4. But ... the bleach is being consumed in the algae fight. The calculated amount will be your minimum starting, you'll need more. Dose, Mix, Test, repeat 'til you get to where you need to be. As for a limit, don't go too far over your shock level but some overshoot will be ok, it will be consumed.

[aylad]

Also, the more often you can test and re-dose to get back up to your shock level, the faster the pool will clear.

Janet

[Watermom]

One other question ----- have you used any algaecide? The foaming that you reported is what made me wonder as some algaecides will cause foaming.

[Cookieman]

No, I haven't used any algeacide yet. I'll get the Chlorine to shock level and let you know how it goes. Thanks

[Cookieman]

After about 25 bottles of bleach, adding enough at night to get chlorine levels to around 20ppm each morning pool cleared in 3-4 days. I was testing twice a day and always added chlorine after sunset. Each night I tested before adding more, and chorine would usually drop back to mid to low teens. Clear as a bell now and trying now to keep it at "best guess" targets for my cyanuric level. Is it time to tackle light brown stain on steps? I have been reading about ascorbic acid and "jacks pink stuff". Thinking I need to stabilize chlorine first....any thoughts. Thanks for the help.