Thanks for a great site I have learned a lot
This is my first post and I hope this is not to long as I wanted to be accurate
I have read the getting started, basic Pool care and ABC of Pool water and many parts of the forum.

I have a 18,000 salt water in ground plaster pool in the shape of 4 part circles.
2 skimmers and 1 middle drain, pool depth from sides to middle is 4 1/2 to 5/1/2 feet deep.
pool pump pressure is at 30psi ( pump pressure has been at 30psi from time we purchased the home July of last year, and owner said pressure was always at 30psi also said sand 2 years old)
SWG is set to 80%, pool has been running from 9:00 am to 6:00pm each day, some days longer.
The pool has no signs of algae in the pool
Pool in Round Rock Texas, temp last 2 weeks mid 80 to mid 90 no rain

Till about 2 weeks ago our pool was picture perfect blue, now
we have a slight lime green color water, water is clear but green with millions of ultra tiny bubbles.
Nothing we do has changed it back to blue.

On all chemicals we followed all directions to a T
16 days ago -
pool readings - a little off but not bad
We tried: to shock the pool double chlorine
Out come: did not work

13 days ago -
pool readings
FC 2ppm
TC 2ppm
Salt 2700
Calcium Hardness 220
Cyanuric Acid 25
TA 80
pH 7.4
Phosphates 300
We tried: Leslie's ultra bright
Outcome: did not work

11 days ago -
pool readings
FC 2ppm
TC 2ppm
Salt 2700
Calcium Hardness 200
Cyanuric Acid 25
TA 110
pH 7.6
Phosphates 300
pool pressure 30psi
We tried: Conditioner to bring up CA
Outcome: CA = 40, pool still light green

7 days ago - we cleaned out pool filter (all the sand and bleached the case) looked at lines none broke,
so refilled with Leslie's sand 5 50lbs bags. hooked all back up fired up pump, 30psi we have 3 2inch lines coming to pump merged into one right before pump.
pool readings
FC 3ppm
TC 3ppm
Salt 2700
Calcium Hardness 200
Cyanuric Acid 40
TA 110
pH 7.6
Phosphates 250
pool pressure 30psi
We tried: Natural Chemistry Pool first aid 9 cup full’s (1 cup for 2,000 gal)
Outcome: pool still light green

6 days ago - added 1 bag salt to raise salt to 3000

5 days ago -
pool readings
FC 3ppm
TC 3ppm
Salt 3000
Calcium Hardness 250
Cyanuric Acid 40
TA 120
pH 7.6
Phosphates 300
took water sample to leslie pool to test for copper - said no copper but still tried it
pool pressure 30psi
We tried: metal free Natural Chemistry 1 leter per 20,000 gallons
Outcome: pool still light green, we vac out pool and back wash filter

3 days ago -
pool readings
FC - 4
TC - 4
Salt 3000
Calcium Hardness 240
Cyanuric Acid 40
TA 90
pH 7.6
Phosphates 300
copper and iron test they said none
pool pressure 30psi
We tried: Supercide Algae Destroyer Stain Remover sold by Leslie (Trichloro-s-Triazinetrione 99.75)
uses 89% Available Chlorine
Outcome: pool still light green, we vacuumed out pool and back wash filter

All above chemicals we recommended buy the pool place or pool cleaning people
we have also vacuumed out and back washed the filter many times.

bubbles, if we have an air leak in the water lines would not our pressure be lower
the last collection basket at the pump with the plastic top the water looks like it always has.


We are at wits end no one has been able to help any suggestion would greatly be appreciated.
Thanks for all the help
Bill

Welcome to the prof33.
Sadly prof you need to go back to pool school (button top right)

You need to shock, shocking is a process not the addition of shock.

http://www.troublefreepool.com/pool-school/shocking_your_pool

Go buy some bleach
Edited to remove naf info

You have algae. The ONLY way to effectively kill algae and take the green out of your pool is with chlorine.

Chlorine will clear your pool. Disregard all other parameters (for now) and study the function of chlorine in Pool School.

Begin the Shock Process as per Pool School and make sure you have plenty of chlorine on hand once you start.....you'll need much more than you think you will need.

This doesn't read true to me.

Combined Chlorine = TC - FC

In all the tests it appears that Combined Chlorine is zero.

The next step may be to see if there is any chlorine usage over night by comparing tests taken after sun down and early morning. If there is loss of chlorine over night then the answer maybe to shock. If not the cause could be something else.

Absolutely Driller, up too early this morning, edited the post to prevent anyone following bad info.

theprof33, welcome to TFP!

If I am following your description correctly: your water is a clear transparent green and adding chlorine has not changed the color at all, nor did adding Metal Free? Also, copper and iron both tested at zero? Finally, you have lots of very small bubbles?

There are basically two possibilities. You might have a low level algae problem that the SWG is keeping mostly under control or you might have copper in the water tinting the water green. The simplest way to distinguish between the two is to do an overnight FC loss test. That requires turning off the SWG overnight and having a FAS-DPD chlorine test to test the FC level very precisely in the evening and again in the morning.

The following paragraph is all based on the water being very clear and transparent and zero FC loss overnight. If it is cloudy or you lost FC overnight, this does not apply. First, start raising CYA to around 80. With CYA in the 40s the SWG is working much harder than it needs to be working. The bubbles are coming from the SWG, and have nothing to do with the color. Some bubbles are normal, though they shouldn't be as obvious as what you describe. Increasing CYA will improve the situation. Second, lower the PH down to 7.2. That might take care of the green color by it's self. If that doesn't work, get two bottles of either Jacks Magic The Purple Stuff or ProTeam Metal Magic and add them to the pool.

If the water is cloudy or you lost FC overnight, which is by far the most likely possibility, then follow the advice teapot and duraleigh gave.

From the direction sheet
Combined chlorine is eliminated by superchlorination.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Can our combined chlorine reading be 0 because of the last chemical (Supercide Algae Destroyer Stain Remover) (Trichloro-s-Triazinetrione 99.75) uses 89% Available Chlorine and other chemicals we put into the pool

POOL READLINGS
4/28/2011 Bill 10:00am
FC-5
TC-5
CA-40
pH-7.6
TA- 90

4/28/2011 (Leslie's) 12:30pm
FC-5
TC-5
CA-40
pH-7.4
TA- 90

4/28/2011 Bill 10:30pm
FC-5
TC-5
CA-40
pH-7.6
TA- 100

4/29/2011 Bill 8:45am before pump started
FC-5
TC-5
CA-40
pH-7.4
TA- 100

4/29/2011 (Leslie's)
9:00am
FC-5
TC-5
CA-40
pH-7.6
TA- 110

We have the Chlorine FAS-DPD Service Test Kit from Leslie we purchased last year when we purchased home we have replaced different bottles from being used up. I have tested our readings against Leslie reading.
When I add 5 drops of R-0003 for sample to turn pink to check for Combined chlorine it does not turn pink I have tried 5 more drops no pink

I have a link with some pictures but am not sure if rules allow link or pictures will look up and if I can will post

again Thanks

If you are reporting FC and TC instead of FC and CC, then I don't think you have the FAS-DPD Service Test Kit, but instead have a DPD kit. Or are you just calculating TC by adding your FC and CC numbers together? At any rate, it is not unusual to see zero or nearly zero CC. I almost always have <= 0.2 ppm CC in my pool where I use a 25 ml sample size for 0.2 ppm resolution of the test. The low CC has nothing to do with using Trichlor. It has to do with the chlorine level relative to the Cyanuric Acid (CYA) level and also to whether you are exposing the pool to sunlight.

I was calculating TC by adding FC and CC

We recommend that you upload pics to Photobucket.com or similar host site, then copy the IMG code and then paste it in your message here - the pic will appear.

Windy day


Three step on side of pool


This shot was from about a foot and half underwater looking to middle of pool


Looking straight down about 2 feet


more pics can be seen at http://www.mynooks.com/pool

again thanks for all the help

It is most likely mustard algae. You have to shock according to the process outlined here. Keep your FC at 40 % of your Cyanuric acid level until the water clears up. That means if your cyanuric acid is 40 ppm, then your FC needs to be 16 ppm. Use liquid chlorine or regular, 6 % bleach.

Bill, according to the test results you have posted, the pool has not been at shock level. I plugged the last set of test results posted into The Pool Calculator, which states your daily FC level is 2-7 and your FC has been 5 or less according to your posts. That level of FC will not kill off an emerging algae bloom, which is what I believe you are in the middle of now. For now keep the CYA at 40. Your shock level is 15. You need to add enough liquid chlorine to raise the FC to 15 and keep it at 15 for at least the next 24-48 hours. That means during the day your are testing every 1-2 hours and topping off the chlorine to keep the FC at 15 during daylight hours. At night top off the chlorine one more time and check it again first thing in the morning. Brush the pool several times a day during the shock process. Also keep the pump running 24/7 during the shock process and clean or backwash the filter whenever you see a 10pt rise in pressure. After a couple of days at shock level we can re-evaluate your pool and decide on the next step.

Where do you get that? I don't see any sign of mustard algae at all in theprof33's pool. Mustard algae grows on the shaded side of the pool walls and forms visually obvious patches. There could be a low level free floating green algae problem, but it takes an overnight FC loss test to determine that.

theprof33, you have some evening and the next morning pairs of test results posted. Were those tests done with the SWG turned off overnight? If so, you have ruled out algae. However, if the SWG was on overnight then algae is likely.

The SWG was off overnight

I was going of trying "Jacks Magic The Purple Stuff" you recommended in a previously post above
any other suggestions?

No, nothing else. Two bottles of Jacks Magic The Purple Stuff should do it.

In the pictures, it shows the pool being vacuumed. If the pool has been vacuumed and brushed, then the algae will be suspended in the water.

I think that there is a filtration issue due to the pressure at 30 psi.

theprof33, in the pictures in the link, there are some pictures of directional eyeballs with some sort of discoloration. Will the discoloration wipe off easily?

JamesW, I don't see any bubbles, just flecks of something floating in the water, which is common enough, though perhaps not at quite that concentration.

The water isn't completely clear, and something is going on there. But the overnight FC loss test rules out algae. There have been several unnecessary chemicals added, and some of them could have contributed to the slightly hazy water. If so it will tend to clear up in a few more days. In any case, I count the haziness as a secondary issue to be put off until after the green is resolved.

The 30 psi reading has been going on for years, which means it isn't involved in the current problem. Most likely it is because of a large pump and small plumbing.