New maintainer with algae on walls

This is my first summer maintaining our home pool and I'm feeling a little overwhelmed already. That being said I'm hoping for some advice on how to deal with what I believe is algae on my pool walls. The pool walls (pebble tec) seem to have streaks of very light green/yellow tinge to them the water seems cloudy/not as clear as it should be. Now for the relevant information:

This is a bean shaped 11,500 gallon pebble-tec chlorine based swimming pool. It uses a Pentair Clean and Clear 420 cartridge system with two Hayward 1hp motors - 1 motor for the filter unit and one for the Paramount in-floor cleaning system.

I will be picking up a HTH 6 way pool kit this evening and have already ordered the Taylor K2006 kit from Amazon. That being said I went to my local pool store and receiving the following stats as a starting point.

Free Chlorine: 4
Total Available Chlorine: 4
Total Alkalinity: 150
Acid Demand: 2
pH: 7.8
CYA: 120
Phosphates: 200

I live in AZ, my filters were flushed/cleaned 3 weeks ago and my pressure has not increased on my filter unit. Temperatures are averaging around 100 during the day droping into the upper 70s at night. Both my filter and cleaning systems currently run for 7 hours each night.

Any assistance you can provide to help me get this under control would be appreciated. I'll be off to the store to pick up some bleach later this evening as well.

Thanks -
SurfaceDreamer

Your chlorine level is way too low for your CYA level. (Take a look at the Best Guess Chlorine Chart in my signature below.) I'm not sure how your pool store got a CYA reading of 120. The test actually can't differentiate values over 100. At any rate, you need to shock your pool up to 25ppm and try to hold it at that level to get rid of the algae. in your pool, each gallon (4 qts.) of 6% bleach will add about 4.8ppm of chlorine. Use that as a reference to help determine bleach doses needed.

Good decision to order the Taylor kit. You're going to need it in order to measure the high chlorine levels you're going to have to run. In the meantime until your kit arrives, you can use a dilution method to force your kit to read a little higher. It is not super accurate and is not meant as a replacement for the good kit but just something to use temporarily. Read about it here: Testing Without a Good Kit

Your pH is ok at 7.8 but if it goes any higher, you'll want to drop it a little with some muriatic acid. Be advised that pH readings aren't accurate at high chlorine levels. With most kits, you need to test pH when chlorine is no higher than 5ppm. With the K-2006, the pH reading should be accurate up to chlorine levels of 15ppm.

Keep your pump running 24/7 while you are trying to clear the pool.

Hope this helps. Come back with any further questions.

Ok - HTH kit picked up, 4.25 gallons of 6% bleach in the pool as of 30 minutes ago, everything brushed down and pump and filter all on. I will test first thing in the AM and see where we are at. As far as the tab floater in the pool... should that be left floating or pulled out during this process? Double and triple checked the filter pressure and it's still operating at normal levels but will keep an eye on it.

Since my filter pressure has maintained steady and not changed so far - do I need to worry about flushing the filters during any part of this process?

Thanks again!

You need to read the Best Guess page linked in my signature, and then make a decision:

+ You can drain 75% of your water, lower your CYA, and then run 'normal' levels of chlorine using tabs, OR
+ You can run CYA=120+, but then raise your FC to 15 ppm, by dosing bleach 1 or 2x per week. You can use a partially filled floater to maintain CYA levels.

1,000s of pools in your area are run that way by service companies who inject chlorine gas 1x per week.

If your filter pressure has not increased, you should not clean it.

PoolDoc - your signature didn't show in your response... may want to check it :)

As for my options after killing the algae - UGH! I just filled the entire pool less than a year ago and my water rates have increased over 50% since then :( Very frustrating. I'm going to recheck the CYA before I proceed with draining the pool.

Any suggestions on where I can find the equipment to perform the pool drain? Is there any place that usually rents the pump for example?

Thanks.

I've decided the following... not necessarily in the following order:

1. ditch the *#($^ pucks :)
2. drain the pool partially and refill
3. use bleach to manage my pool going forward (unless there is another way to manage without raising CYA)
4. Pray my family doesn't mutiny on me and hang me from the pool umbrella for messing up their summer cool off spot ;)

My OTO kit this morning still showed TC over 15 (using the testing without a good kit method - double dilution) and pH at 7.8 however I don't think that will really matter since I'm partially draining the pool and all my chemistry will change from the dilution. That being said can I simply start with the partial drain now or should I wait for more shocking to be completed before I start the partial drain? I just want to make sure I don't make the algae issue any worse. I found a pump rental at a local hardware store and was going to move forward with using that to drain the pool.

Thanks!

Go ahead and start draining. By the way, the link Ben wanted you to read -- Best Guess Chlorine Chart --- is in my signature below.

Thanks Watermom! I had looked at the link in your signature line and made my determinations there :) Just wanted Ben to know that his signature line wasn't showing (at least for his response in this thread). I'll start draining the pool in the AM and go from there. Hooray me!!! <--- notice the sarcastic enthusiasm

When we post, we have the option to show our signature or not. We try not to show it every single time because all those "blue banners" are pretty bold. So, we typically just show the signature occasionally instead of every time we post. On your post, Ben must have just unchecked the box and that is why it didn't show on that particular post of his.

SurfaceDreamer,

I don't want to try to talk you into something you don't want to do. But, if your family is ready to swim, you don't have to drain. So long as you maintain your K-2006, so you can test accurately, there's no real downside to running a high CYA / high chlorine pool . . . especially if you establish a algistatic borate level.

And, by going that route, you can use up your trichlor tabs!

Ok, there are a few downsides:

1. If you take a water sample to a pool store, they will freak out, and tell your your pool is going to sneak into your house, and murder your and your family at night (or something to that effect)! ;)

2. If your buddy comes over, notices how clear your pool is, and asks you how you do it . . . he'll give you a really weird look, if you actually tell him.

3. You won't need to add chlorine but once a week. With all that extra free time, you may do something that gets you in trouble.

The irony is, the same neighbor who thinks you're nuts, may have hired PoolChlor of Arizona to do the VERY SAME THING to his pool . . . using -- OMG! -- chlorine gas!

Ben,

Thank you for following up. I retested the pool at the local store around noon and got the following numbers:

Free Chlorine: 5 (I know it's > 15ppm at this time)
Total Chlorine: 5 (I know it's > 15ppm at this time)
Calcium Hardness: 400
CYA: 120
Total Alkalinity: 150
pH: 8.0
Total Dissolved Solids: 1500

I know the "what would you do" questions are typically subjective to each individual but I'm trying to look long term and determine what is in the best interest of the pool and its maintenance needs going forward. I'm concerned that by finishing out the 70+ lbs of tabs I have that I'll just be compounding my future issues and besides - I can sell the tabs for what I paid for them so I wouldn't be out anything. Couple that with the fact that I have a child who has very sensitive skin; I think it would be best to do a partial drain and get the numbers back down. If I look at this reaslisitcally I'm just whining about doing something that my family is complaininig to me about messing up in the first place... of course I'll never admit that to them - HA!

I'll rent the sump pump tomorrow and get to work. If there is something I'm missing please let me know! Thanks again.

One final question for my own clarification - outside of dilution (and of course rare earth elements that I can't get anyways)... is there any other cost effective way CYA can be lowered in a pool? From my reading I don't believe there is but wanted to ask.

You remove phosphates with lanthanum (a rare earth metal); you can remove cyanuric acid with melamine, an organic base. But, you don't want to do so: it makes a huge mess.

Draining and refilling will put your pool back in service much faster.

Ok - the partial drain is almost complete. On to my next question... since I've got the pool partially drained is there anything I can do to the walls in this state that would be beneficial in combating the algae I had forming on them? Anything else you would recommend I do while the pool is in this state?

If you have any black algae spots, pressure washing them, and then rinsing with bleach would be good. Otherwise, nothing occurs to me.

Ok - partial refill completed this morning. Here are the results from my OTO kit (Taylor K2006 kit not here yet) and my local pool stores tests...

OTO test:
Chlorine: 6 (single dilution method)
Alkalinity: 130
pH: 7.8
CYA: < 30 (the tube only went to 30 and I could still see the dot albeit faintly - my best guess is 20-25 CYA)

LPS test:
Free Chlorine: 5
Total Avail Chlorine: 5
Alkalinity: 120
pH: 7.7
CYA: 25
Calcium Hardness: 210
Phosphates: 50

Looks like things are fairly balanced except a slighly low CYA. I'm not quite sure how these numbers are what they are considering the amount of water I drained but both tests (LPS and OTO kit) came up very close. I made sure to get the samples for the tests 6+ inches under the surface of the water. Anything else you can recommend I do prior to opening for a dip?

Also, being I have a lower CYA am I correct in assuming I will need to add bleach/chlorine more often? Thanks again for all your assistance!

Yes, you will probebly have to add chlorine more often, but if you'll test it daily it won't take long for you to determine how often that needs to be.