All levels normal, pool still dark green

[msdunkel]

The pool is a 30k gallon vinyl lined chlorine cleaned pool with a sand filter. We've been getting a LOT of rain over the past month and the pool has went from crystal clear to dark green over the past 2 weeks. We've shocked 3 times and used a Leslie's product called Green to Clean in the pool and it keeps getting worse.

Here are the pool's levels
FC: 5ppm
TC: 5ppm
pH: 7.2
Alkalinity: 120 ppm

Other than the chlorine being slightly high the levels are what my testing kit says are normal, yet the pool is nasty. Any ideas? I've read Pool School already. Twice.

 

[mknauss]

Welcome!

If you have read pool school you know we advocate self testing your water with a properly designed test kit. Do you have one?

You also know that FC depends on CYA. What is your CYA? Not what the pool store tested, what you tested.

You also know you need to SLAM. So make sure you have the proper test kit, I suggest the TF100 from TFTestkits.net, and load up on bleach and SLAM.

Take care.

 

[Akathisia]

Here are helpful links to things that mknauss was referring to:
Pool School - Test Kits Compared
Pool School - Chlorine / CYA Chart
Pool School - SLAM - Shock Level And Maintain

It's really important to invest in a good test kit and to understand how the FC/CYA relationship impacts your pool. Keep coming back with questions and you will get through this and enjoy your pool.

Also, if you could add helpful info to your signature as outlined in the next link it can help people help you.
Pool School - Read This BEFORE You Post

 

[msdunkel]

Thanks guys, I hadn't read all the links from the main pool school page. I'll get on it and report back.

 

[msdunkel]

Ok, I didn't do anything to the pool for fear of throwing more money away (last round of shock treatments was $200 and did nothing). That said, the pool is darker than my grass but doesn't look slimy or smell bad (yet). Here are my readings:

FC: 4.5
CC: .5 (almost 0, the water was just ever so slightly pink without any added drops)
CH: 325
TA: 110
CYA: 90
pH: 7.5

I appreciate any advice to make my money pit usable again.

 

[mknauss]

Great job on getting a complete set of test results.

Your CYA places you at a decision point. You can SLAM at that high of CYA, but it is not recommended. Your shock level FC would be 36 ppm. You will use alot of bleach and testing reagents.

You should investigate whether a partial drain and refill is possible. You have a vinyl liner pool. So the most you can drain at one time is only to the point of leaving 1 foot of water in your shallow end. Do you have a shallow water table (water in the ground near surface)? That makes a difference.

You most likely will need to do two drain and refills to get your CYA to 40 or so.

You did not say which test kit you have. You will be using a lot of testing reagents during this process. At the minimum, you should order more FAS-DPD reagents now. TFTestkits.net sell them and you should get them early next week.

I know you will have more questions -- post them and we will do your best to help you.

Take care.

 

[msdunkel]

Great job on getting a complete set of test results.

Your CYA places you at a decision point. You can SLAM at that high of CYA, but it is not recommended. Your shock level FC would be 36 ppm. You will use alot of bleach and testing reagents.

You should investigate whether a partial drain and refill is possible. You have a vinyl liner pool. So the most you can drain at one time is only to the point of leaving 1 foot of water in your shallow end. Do you have a shallow water table (water in the ground near surface)? That makes a difference.

You most likely will need to do two drain and refills to get your CYA to 40 or so.

You did not say which test kit you have. You will be using a lot of testing reagents during this process. At the minimum, you should order more FAS-DPD reagents now. TFTestkits.net sell them and you should get them early next week.

I know you will have more questions -- post them and we will do your best to help you.

Take care.

I got the TFT-100 with the XL option. Because of all the rain we've been getting, we've had to drain the pool 4-6" a couple times over the past month. With evaporation accounting for at least another 1/2" a day I feel like we've probably already drained and refilled the pool (with rainwater). Is this sound logic?

 

[mknauss]

The rain water helps. But evaporation does not with CYA. It does not leave your water with evaporation.

The amounts changed out due to rain is not enough. It most likely means your CYA was higher before those drains due to rainfall.

You still need to lower CYA to make your SLAM more manageable. But that is up to you.

Take care.

 

[tim5055]

I got the TFT-100 with the XL option. Because of all the rain we've been getting, we've had to drain the pool 4-6" a couple times over the past month. With evaporation accounting for at least another 1/2" a day I feel like we've probably already drained and refilled the pool (with rainwater). Is this sound logic?

Evaporation does not count. When water evaporates the CYA stays behind.

The only way CYA leaves is if you pump water out of the pool.

While many storms can "feel" like it, 4" - 6" is almost the output of a tropical storm.

The only way to be sure where you are now is to test eh CYA again.

 

[msdunkel]

Thanks. No idea how deep my well is or how much water is there. Too risky/expensive to burn out the pump or have to drill a new well, so draining the pool is off the table.

 

[mknauss]

Thanks. No idea how deep my well is or how much water is there. Too risky/expensive to burn out the pump or have to drill a new well, so draining the pool is off the table.

There is your answer. Up to you but I would run a diluted CYA test to confirm you are only at 90. See Step 8 in Pool School - CYA

To SLAM you need to add muriatic acid to get to a pH of 7.2. Then start adding bleach/liquid chlorine to take your FC to 35 and maintain that. Test/dose every couple hours until your FC starts to hold.


Good Luck!

 

[msdunkel]

There is your answer. Up to you but I would run a diluted CYA test to confirm you are only at 90. See Step 8 in Pool School - CYA

To SLAM you need to add muriatic acid to get to a pH of 7.2. Then start adding bleach/liquid chlorine to take your FC to 35 and maintain that. Test/dose every couple hours until your FC starts to hold.


Good Luck!

Thanks for the advice. So if I can't drain will my CYA always be extremely high, or will it come down on it's own at some point?

 

[mknauss]

As long as you do not add any CYA containing products (trichlor, dichlor, stabilizer, conditioner, etc) it will come down on its own.

The more you can capture rain water and drain off before the rain the better off you will be.

To get the CYA to 40 or so to make the pool manageable will take well into next year, most likely.

Take care.

 

[msdunkel]

Thanks again. BTW I just did a diluted CYA test and the results were variable. I'm not sure I'm doing it correctly, the longer I wait it seems the sediment in the tube settles and I can see the dot better. Immediately after shaking the level is around 180, about a minute later it was about 140. Also not sure how sunlight/shade affects how well I can see the dot.

 

[mknauss]

Pool School - CYA

Stand outdoors with your back to the sun and hold the view tube at about waist level.

Bright sun is best. I also fill the tube to a line, say 100, then glance at the dot, if there, fill to 90, glance, etc.

 

[tim5055]

Thanks again. BTW I just did a diluted CYA test and the results were variable. I'm not sure I'm doing it correctly, the longer I wait it seems the sediment in the tube settles and I can see the dot better. Immediately after shaking the level is around 180, about a minute later it was about 140. Also not sure how sunlight/shade affects how well I can see the dot.

Shake the bottle for 30 seconds and conduct the test. You should conduct the test in full sun, but with your back to the sun, with the vial at waist height looking down into the vial.

 

[msdunkel]

Thanks guys. And when we're talking adding bleach to the pool, is there a chart how much I need to add or is it trial and error. Also, we're talking just basic bleach that I'd use to clean my whites that I can buy at the grocery store? Also, anything wrong with adding too much? Bleach is cheap, I don't mind adding too much if there's no downside other than the cost of the bleach.

 

[mknauss]

You use PoolMath to determine how much bleach.

Be sure the bleach is 8.25% sodium hypochlorite. You also want to get it at stores that keep it inside and have high turnover. Walmart is perfect.

However, you will use a lot of bleach to attack this at your high CYA. In fact, if your CYA is 140 or so as you said from your diluted test, it will be impossible.

At a CYA of 90 - it will take 13 jugs of regular bleach to start. I suspect it will take well over 100 jugs to complete the SLAM.
At the 140, it is not recommended to even try.

Take care.

 

[msdunkel]

We called the company that inspected our well when we bought the house and they said it should be ok as long as we just do a 1 hour on, 1 hour off duty cycle to avoid pulling up sediment from the well. Draining the pool now.

 

[mknauss]

Good to hear.

Good luck.

Remember from a previous post --

You have a vinyl liner pool. So the most you can drain at one time is only to the point of leaving 1 foot of water in your shallow end. Do you have a shallow water table (water in the ground near surface)? That makes a difference.