Trouble with Chlorine levels and recurrent yellow algae

[timthek]

So, I've been reading here on TFP for probably over a year. I probably should've posted last year when I was having issues the first time....

I have a solid Taylor test kit (though I just had to reorder my CYA reagent), test strips for backup, and a local pool store with full time staff who at least know how to test.

My current readings, confirmed by the pool store's results, are:
FC: 6
TC: 6
CH: 280
CYA: 80-100 depending on who you ask
ALK: 80-90
pH: 7.2
Phos: 400

Now, my pool is about 25,000 gal and gets full sun all day. I also get a lot of vegetation in my pool from flowers and leaves to pine needles. Pool surface is "Pebble Tec aggregate. DE filter runs 4-6hrs per day. Water temp ~ 83F. Hayward Automatic Chlorinator using 3" tablets.

Recently, my chlorine levels dropped to around 2ppm and boom, the yellow algae appeared. Shocked the pool up into the teens, brushed daily. Also, and I know many of you don't feel it necessary, but my Phosphates were in the 2000+ range, so I treated the pool with PhosFree and got it down to 400. Vacuumed and backwashed. I don't feel like I need to get that number to zero.

My problem is maintaining my chlorine levels without ending up with too much stabilizer. Last summer my CYA numbers were nearly 200 and I needed to drain and fill half my pool to get them back under 100. With CYA that high I couldn't keep up the chlorine level to keep the algae at bay at all last summer.

I try to keep the chlorinator set around 3 because I have had issues with too much stabilizer in the past. Maybe I'm wrong on that approach? I have been shocking every other week with 2lbs of shock (powdered). I also use non-chlorine shock in the "off weeks".

Suggestions / directions?

I "think" I should be aiming for 7ppm FC based on my CYA levels. How would you recommend I get and stay there? Stick with the tabs and increase shock treatments? Dump the tabs and use something else? (I don't think I can convert to SWCG because of the natural stone pool surround)

Thanks,

-Tim

 

[chiefwej]

You are seeing first hand why you can not use pucks as your primary source of chlorine. Every puck you use adds more stabilizer along with the chlorine. The chlorine gets used up, but the stabilizer is left in the water. When it builds up too high, you must drain.

What we teach here is to use liquid chlorine or SWG as sources of chlorine, and carefully monitor pool chemistry. This requires testing and understanding a bit about the chemistry, then adding only what is needed. No pool store methods and no pool store "magic potions".

You will need to decide if you want to join the thousands of pool owners who use the tools and methods recommended here, and learn how to manage your own pool. That means accurate testing with a good test kit learning that you only add what the pool needs, and rejecting any advice from pool stores. You can get started by reading the info contained in "Pool School". That's the button on the upper right of this page. It may take a bit of study and re reading for it all to begin to fit together and make sense, but it will be worth it.

Disregard any pool store testing. It has proven time and again to be inaccurate and the worst is their CYA testing. Test strips are worthless. Only you running proper test with a good test kit provides reliable and repeatable results.

 

[zea3]

Hi, welcome to TFP! Your CYA is still too high. You are using enough chlorine to keep the algae from turning the pool green, but not enough to kill it all off. If we say your CYA is 90, your FC target range is 4-12ppm. You want to keep at the high side of the range to account for normal 2-3ppm per day chlorine loss. If you only dose as high as 7ppm you could easily drop below 4ppm in one day, setting up another algae bloom.

I would remove the pucks from the feeder and lower the CYA level to 50ppm max. Use liquid chlorine to dose the pool and do not use powdered shock. It will either be dichlore based which adds CYA or cal-hypo based which adds calcium.

An option you may want to consider is a Liquidator or a Stenner pump. These items automate the use of liquid chlorine so you do not have to add it by hand every day.

 

[timthek]

Thanks for the advice. I do have a solid Taylor test kit that I have supplemented with additional tests. I think it's the K-2105, though I recently added a chlorine comparator that goes up to 10ppm as the one it came with only goes to 2.5!

As for the pool stores, I agree that they are hit or miss, but one in particular near me (it's a Leslie's but I only use them for testing!) has a very knowledgeable staff and they use the same Taylor test kits I do and I watch them carefully. I use them just to confirm my readings or if I run out of reagents and haven't gotten my shipment.

I don't (typically) buy into the "add this to fix that" craze, though I find some chemicals to be helpful (such as getting rid of heavy pollen accumulations in the early summer).

As for chlorination, I've been trying to move away from the pucks, but I don't want to have to dump bleach in my pool on a daily basis. The Liquidator sounds very promising though. I had not heard of it previously. At $200 it would probably pay for itself in 2 seasons when comparing the costs of shock and tablets to liquid chlorine. Thanks for that advice. A SWCG is probably not in the cards thanks to the high initial cost and the risk of damage to my flagstone coping.

While I look into the Liquidator a little more, I'm going to try to maintain my FC at around 10ppm and hope my CYA doesn't get too high again.

 

[Beens]

Make sure you maintain it with liquid chlorine while you do your automation research or there won't be any need to hope because it's guaranteed to get too high if you're using dichlor powder or trichlor pucks. :-(

Technically you could just keep using pucks forever...if you don't mind a lot of draining and refilling to lower your CYA.

Make sure you test your CYA yourself as soon as your refill gets in.

If you're already seeing signs of algae you're going to need to go through the SLAM process. The higher your CYA the more chlorine it's going to take to get to the right levels so...#1 think about lowering CYA before you start a SLAM and #2 you're going to need to add the FAS/DPD chlorine test to your kit so you can test chlorine levels above 10. (It is a drop based test that uses R-0870 powder, R-0871 drops and R-0003 drops to test for CC)

 

[DaninFLA]

The Liquidator sounds very promising though. I had not heard of it previously. At $200 it would probably pay for itself in 2 seasons when comparing the costs of shock and tablets to liquid chlorine. .

and don't forget the costs of drain and refills. if you really want to avoid issues moving forward the liquidator is a great idea, but you also need to get your CYA back down to range. if you keep your FC at 10 or above, you will not be able to test for pH and make adjustments since the pH test doesn't work if your FC is 10 or higher. and you don't want to have to drop your FC lower just to test pH.

 

[gwegan]

Your Pool is a bit big for a Liquidator. It will work but you will have to add chlorine regularly and run the pump enough to get it to flow. It won't work if you have a vs pump and run it on low -- it might work if you have a two speed pump and run it on low.

What kind of pump do you have?

A Stenner pump is a better option for your pool in my opinion.

Cut out the tabs --go with the TFP method with liquid chlorine -- my pool is clear and I don't have to shock --

 

[timthek]

Your Pool is a bit big for a Liquidator. It will work but you will have to add chlorine regularly and run the pump enough to get it to flow. It won't work if you have a vs pump and run it on low -- it might work if you have a two speed pump and run it on low.

What kind of pump do you have?

A Stenner pump is a better option for your pool in my opinion.

Cut out the tabs --go with the TFP method with liquid chlorine -- my pool is clear and I don't have to shock --

My pump is a pentair single speed.

Specs: 3/4 HP, 1.27 sf, .95 SFHP

Because of all the vegetation and debris my pool gets, I usually run it 6hrs a day. Is that going to be enough to run the liquidator? Let's assume I can get my CYA down to 50, how much liquid CL is it going to take per day and how many hours of run time?

Seems like a stenner pump is a lot more of a setup and 2-3x the cost?

 

[timthek]

Make sure you maintain it with liquid chlorine while you do your automation research or there won't be any need to hope because it's guaranteed to get too high if you're using dichlor powder or trichlor pucks. :-(

Technically you could just keep using pucks forever...if you don't mind a lot of draining and refilling to lower your CYA.

Make sure you test your CYA yourself as soon as your refill gets in.

If you're already seeing signs of algae you're going to need to go through the SLAM process. The higher your CYA the more chlorine it's going to take to get to the right levels so...#1 think about lowering CYA before you start a SLAM and #2 you're going to need to add the FAS/DPD chlorine test to your kit so you can test chlorine levels above 10. (It is a drop based test that uses R-0870 powder, R-0871 drops and R-0003 drops to test for CC)

I'm not showing algae yet. I just dosed the pool this morning to be safe.

I don't want to do the drain and refill method...seems wasteful at a minimum. I think the liquidator is my best bet in terms of keeping algae away and cost down. I don't mind if I have to buy 5 gallons a week of liquid CL, that seems better than $100 buckets of pucks that only cause headaches, or manually dosing the pool daily.

 

[tim5055]

I have a similar sized pool and have full sun all day. Right now I'm using about 3 quarts a day.

I have read stories from folks having too many problems with the Liquidator, mainly from flow issues and valve issues so I went with a Stenner Pump. My Stenner Install - July 2014

But, a Stenner adds about $300 over a liquidator once you get all the parts

Now my recommendations to you, take them as you see fit

Go with the Stenner. It is easier to control flow changes as you need to make changes. Remember, your chlorine usage is not static. Early in the Spring you use less, top of the summer you use more. I can just dial up the flow on my adjustable rate Stenner.

Order the FAS-DPD individual test. TFTestkits.net has them, but they are available at other places. The color comparison tests are not accurate enough for my next recommendation.

Conduct an Overnight Chlorine Loss Test (instructions in Pool School). From your description of the history of your pool I believe you have something growing in the water, but are holding it at bay with just enough chlorine. If you miss adding chlorine for,a couple of days or as your CYA continues to rise with tab usage it is going to,rear its ugly head with cloudy/green water.

 

[timthek]

I have a similar sized pool and have full sun all day. Right now I'm using about 3 quarts a day.

I have read stories from folks having too many problems with the Liquidator, mainly from flow issues and valve issues so I went with a Stenner Pump. My Stenner Install - July 2014

But, a Stenner adds about $300 over a liquidator once you get all the parts

Now my recommendations to you, take them as you see fit

Go with the Stenner. It is easier to control flow changes as you need to make changes. Remember, your chlorine usage is not static. Early in the Spring you use less, top of the summer you use more. I can just dial up the flow on my adjustable rate Stenner.

Order the FAS-DPD individual test. TFTestkits.net has them, but they are available at other places. The color comparison tests are not accurate enough for my next recommendation.

Conduct an Overnight Chlorine Loss Test (instructions in Pool School). From your description of the history of your pool I believe you have something growing in the water, but are holding it at bay with just enough chlorine. If you miss adding chlorine for,a couple of days or as your CYA continues to rise with tab usage it is going to,rear its ugly head with cloudy/green water.

Thanks for the recommendations.

I did test my chlorine loss overnight and it was about 2ppm (somewhere between 5-7 last night down to between 3-5 this morning: Call it 6 down to 4). I hit the pool with a pound of 65% Calcium Hypo this morning and another pound this afternoon. I have to get to the pool store to get some liquid CL this weekend. In the meantime I'll continue to hit it with the granulated Cal Hypo tonight until I get the liquid.

I ordered an FAS-DPD test kit this afternoon.

EDIT: I tested my CYA and got ~ 110ppm. (puck chlorinator is OFF)

I'm thinking of going with the liquidator despite the issues you mentioned just for ease of setup and cost consideration. I'll read through your experiences with the Stenner and give that consideration though. Thanks again.

 

[tim5055]

Yea, with 2 FC loss overnight something organic is in the water. It appears you are catching it early, so a SLAM is needed and hopefully will go quickly. Read through the article in the SLAM process. Just shocking the pool like you are doing dows not keep,the FC high enough/long enough to,assure everything in the water is dead.

 

[timthek]

Yes, but with no liquid CL on hand, 3 kids and temps in the 90's a SLAM isn't practical right now. Especially with CYA at 110. I am going to try to maintain elevated CL levels for a few days and then either SLAM, change 1/2 the water, or both. Weather and family permitting.

Edit: Also my FAS-DPD kit won't get here until Monday afternoon at the earliest...

 

[timthek]

So I got "spousal approval" to go the Stenner route. I'm not sold on that over the liquidator so I'll probably start a new thread over in the automation section to solicit advice.

Thanks!

 

[timthek]

Finally got my FAS-DPD kit today. Turns out I've been running in the 20's since the weekend and have almost no combined chlorine. I guess that's good. I'll be doing an overnight chlorine loss test tonight to see where I am on that. I'm hoping with FC in the 20's all week I was able to knock out whatever was setting up residence in my pool. If not, I'll slam it. I also need to dump & refill half my pool. So I have that going for me....

 

[DaninFLA]

cool, would definitely keep your FC levels up. plenty of people here swim thru their SLAM when its like yours (i.e. not a green pool). if you CYA is 100, then your SLAM FC level is 39. If you wan to swim throughout, maybe keep your FC level in the mid 30s. not as quick and effective as a SLAM but should help until you can drain and refill.

wouldn't go by having no CCs as an indicator that you don't have a algae issue starting. pretty common to see CC of zero even with green pool sometimes. on your last OCLT, you went from 6 to 4, which is a 33% drop in FC overnight last time. that's significant. but you have kept your FC up for the past few days, so who knows. If you lost that same percent with a FC of 20 that would be 20 to 14. I would get your FC up in the 30s for your OCLT.

 

[timthek]

So, I've been testing morning and night. First afternoon was at 22 (44 drops) and this was after adding no chlorine for more than a day. With the amount I had been adding on a daily basis I have no doubt I was in the 30's for several days. Next morning was at 21. Last night I was at 19 or 17 (tested twice). This morning I was at 16 or 19. Tonight I'm at 14.5 or 16. I find the results to be not particularly accurate. I try to get the 10ML line right on the meniscus of the test tube each time, but my results on back to back tests can vary by 4 drops (2ppm).

All I can tell is I use about 2ppm per day and may or may not lose any overnight. I think at this point I am going to wait until tomorrow morning and see what my FC level is. If it is in the 14-16 range again I'm fairly confident I knocked everything out. I'm going to try to hold the FC at 12-14 until I can drain and refill. I'm not sure when I will be able to dump 1/2 the water and refill though since it would probably take me 24+hrs to do it. At my water cost that would be about $125 to do half my pool. I looked into having it delivered so as not to have the down time but it is way more expensive at $610.

I'll say this, my pool has never been this clear for this many days in a row!

 

[tim5055]

Tim,

I hate to sound like a salesman, but do you have a SpeedStir? Using it I find that my testing is spot on every time. Tie that in with a Sample Sizer and you should get the same result time after time.

Now to your current results, 2ppm loss per day is very common.

 

[timthek]

I had to look up what those things are....so no I don't have them. The stirring I don't mind, the sample sizer could be useful.

That said, I hit exactly 14.5 again this morning. I'm pretty confident that I'm not losing any CL overnight at this point. I'm going to move ahead maintaining a FC level of 12-14ppm until I can drain and fill.

 

[tim5055]

I had to look up what those things are....so no I don't have them. The stirring I don't mind, the sample sizer could be useful.

That said, I hit exactly 14.5 again this morning. I'm pretty confident that I'm not losing any CL overnight at this point. I'm going to move ahead maintaining a FC level of 12-14ppm until I can drain and fill.

A big part of accurate testing is constantly stirring, it really helps with your tests. I have both and love them.

How comfortable are you that the CYA is 110? Did you get that with and extended/diluted test or "it's just a little over 100"?

I started with 200+ CYA and took about 18 months to work the CYA down to my current 50. You just have to be diligent in keeping the FC where it needs to be.