new user, old pool, trouble with algae

I am having an especially difficult time with algae this year. I have a 24000 gallon inground vinyl liner, sand filter, 3/4 HP pump. When I took the cover off, water was dark green and cloudy. Usually lots of shock clears it up in about a week, but after 3 weeks I'm still dealing with light green cloudy water. Here's what I've used so far:

1. an entire 40 lb bucket of granular shock
2. 15 lbs of alkalinity up followed by 30 lbs of soda ash to get ph to 8.0 so I could use "green to clean" (had good results in the past)
3. 1 container "green to clean" with 8 lbs shock, followed by another 6 lbs shock 12 hours later
4. 1 bottle "pool magic" to eat up the dead algae (no results)
5. changed out sand in filter
6. 10 lbs power powder
7. running pump 24/7 on "recirculate" (before today i was filtering)

here's what my tests show (pretty consistent for the past few days)
TC >10
FC >10
ph - between 7.8 and 8.0
TA 180
CYA 150

any advice? i've removed as many leaves as i can with my "blue devil" but who knows what's down there since i can't see the floor of the pool. also brushing daily. just give it more patience? i'd be tempted to drain and start over, but my main drain doesn't work and draining is a nightmare! i know my circulation is a problem without main drain, but i've been circulating through the skimmer only for 5 years, never had this much trouble before.

HI, and welcome to the forum!!

My first piece of advice is to slow down a little bit and stop throwing things at the pool trying to get it clear. The second piece of advice is to stay away from the pool store that is selling you all this stuff!!

I'm assuming the granular shock you used was dichlor, and that would explain why your CYA is so high. In order to get the pool cleared up, you'll need 4 basic things: 1 )a good test kit (see the link for test kits in my sig) because testing is going to be crucial to getting the pool cleared, and you'll need to be able to test HIGH amounts of chlorine, 2) enough bleach to maintain a shock level of 25 ppm of chlorine for an extended amount of time, 3) a working pump and filter system, and 4) LOTS of POPP (pool owner patience and persistance).

You'll need to stop using any form of stabilized chlorine, which is why we recommend bleach. The increased problems you have with algae this year are almost certainly happening bvecause you're not keeping your chlorine high enough. Take a look at the "best guess chlorine chart" link in my sig for more info about that. Also, I gather that you're using test strips for testing, and they're simply not going to work while trying to clean up a messy pool. Can you let us know what type of pump/motor, and what size/type of filter you have?

Im not expert but isnt a 3/4 hp motor a little small for a sand filter on a 24k gallon pool? If it worked in the past i doubt that its your problem but it does seem a little small. I recently had the same issues and figured the sand was just old. I ended up just replacing the filter and putting in a new pump. I increased the pump from 3/4 to 1hp and it looks great now :) (i used just shock, yellow out and chlorine tablets)

Yes, I'm a pool store addict. Trying to rehabilitate, since the worse off my pool is, the more money they make! While I'm waiting on a test kit, here's what kind of pump/motor I have:

New (as of this season) 3/4 HP pump - not sure what brand
Hayward S220T sand filter with 250 lbs sand - new filter in 2010, new sand as of Monday

Thanks for your help :)

A smaller pump with larger filter is always better than a smaller filter overdriven by a pump that's too large. The equipment gurus should be along shortly ( Pooldoc? mas985?) to verify this, but I would think a 3/4 HP is fine for that size pool. Even though it'll take longer to turn the total water volume over, the filtration actually should be better.

With a CYA of 150, then you'll need to get the chlorine levels up to 25 ppm, and keep them there by testing and adding more chlorine as often as you can during the day, until the green clears up. I would also keep the pump running 24/7, brushing the pool daily, and keep an eye on your filter pressure, backwashing as needed, but not until you see an 8-10 psi rise in pressure. Considering your CYA levels, I would strongly advise you to use bleach, or liquid chlorine. In 24K gallons of pool water, each 2 gallons of 6% bleach will raise your chlorine by 5 ppm, so you can use that as a guide when figuring your chlorine additions. As I said before, though--you're going to need to be able to test high chlorine levels to get this one cleared up.

I've had the house/pool for 8 years, and never had a problem with the 3/4 HP pump before now. I should say I just replaced the motor, not the pump. I'm getting a test kit for high chlorine levels and some bleach today, I'll report back as soon as I can retest.

Should I be running the pump on filter or recirculate? I won't need to backwash if it's just on recirculate, right?

You won't need to backwash if it's on recirculate, assuming everything is plumbed and working like it should. NOrmally we would advise people to run the pump on filter while the mess is being cleaned up, and with a larger filter on a smaller pump, I'm still inclined to advise you that way. However, this year we've had a ton of folks who are having problems clearing up the dead algae once it's killed, and Pooldoc believes that sometimes it's due to forcing the dead stuff through the sand and actually having it break up into smaller pieces than the filter can catch. So....if it were my pool, I'd probably keep it in filter mode. However, if you want to leave it on recirculate until it's all dead and THEN switch back to filter to get it all out, you can do that too. Either way works, but if your filter is efficient at getting the dead stuff, then the recirculate option may just take a little longer.

Janet

I am not the equipment guru around here by any means. But just wanted to share what I have on my pool since the pump size for this pool is being debated. I have a 27ft AG pool (approx. 19,300 gallons) and I have a 1/2 hp full-rated inground pump and it works just fine. I'm inclined to think that a 3/4hp on your pool should be plenty. Just my $0.02.

Welcome to the forum!

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Originally Posted by ksukris

I'm getting a test kit for high chlorine levels and some bleach today, I'll report back as soon as I can retest.

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The locally available "high chlorine" tests are not what you need, 98+% of the time. Get a K2006 or K1515 (test kit page linked in my sig) online. Meanwhile, get a local OTO (see kit page) kit for now. If the Walmart's in your area have the HTH 6-way, those are an excellent value (they are a private label Taylor kit!).

I ordered a FAS-DPD kit from Amazon, found out the hard way they aren't sold at the pool stores! I did get an OTO kit, but had to dilute the water substantially to get a reading. Assuming my dilutions were accurate, I'm somewhere around 35 ppm on chlorine. Running filter and keeping an eye on pressure to backwash, and brushing daily. Would it hurt to dump in a couple bottles of bleach or should I save it for when my chlorine drops? I'll test again in the morning and see if it's still around 35 ppm.

Unless you have EXTREMELY high stabilizer, 35 ppm is more than enough. If your chlorine level gets too far ahead of your stabilizer level, you can begin bleaching your liner. That may happen anyhow -- liners vary widely and unpredictably in their color-fastness -- but unnecessarily high chlorine can certain accelerate it.

An update: Wednesday night and Thursday morning chlorine level was holding at 35 ppm. By Thursday night, it had dropped to about 24 ppm, so I added my first dose of liquid bleach and raised it up to 32 ppm. This morning, I was reading back around the 24 ppm range, so more bleach went in. I maybe detect a small change in the water color (still cloudy light green), but can't be certain. Equipment is running fine, I've backwashed a couple times and continue to sweep. The water seems to be using the bleach faster than it was using the powder shock, does this indicate anything? Shouldn't I be seeing some results with these high chlorine levels?

Without knowing what your stabilizer level is, it's hard to say what should be happening. If your CYA=400 . . . then, no, 35 ppm won't be enough. That's why we want a CYA test. Did you check to see if a HTH 6-way was available in your area?

I'm reluctant to tell you to go higher, lest your have LOW CYA, and bleach your liner. By the way, with OTO, 35 ppm is dark orange, without any dilution.

One quick check: are you using DISTILLED water to dilute? Most tap water has chlorine, more than enough to cause testing error, if you are diluting.

CYA tested to 200 ppm. Yikes! I've been keeping shock level around 35 ppm of chlorine. Yes, I'm using distilled water to dilute, I did a quick check with full-strength pool water and got a deep orange color. As for my liner, it only has a couple years left anyway, is there any other danger to overshocking? I don't plan on jumping in anytime soon :) Just stocked up on more bleach, in the past 6 days I've added 16 gallons.

With 200 ppm CYA, 35 ppm is NOT over-shocking . . . if the water is clear, feel free to swim.

(Don't tell the local health inspector -- he hasn't read the Best Guess page -- but the local country club pool I service was at CYA=100 and FC=28 most of this past weekend. Over 400 people swam, with no complaints!)

After lots of reading on this forum and on poolsolutions.com, I've decided I don't want to deal with 200 ppm CYA. I've been a pool store junkie for years, and there is no telling how much crap is in my water besides the high CYA. I'm going to drain and refill. I'm aware of the issues with draining (floating pools), but that isn't a problem in my area. I lost all the water a couple years ago over the winter when there was a hole in the liner, and since the cover was on I have no idea how long it had been like that before I noticed it! No damage to the walls of the pool then, so I'd rather pay the $200 for new water from the city and start fresh. Once I have new water in, I'm going to use the dichlor I still have laying around until my CYA is 30 ppm, then switch to bleach. I'll add a little bleach as I refill to make sure I don't get an algae bloom before I can get the equipment running. Is this crazy? It doesn't sound like I have many options unless I want to deal with high CYA.

Oh, and my liner only has a couple years left in it anyway. Has some wrinkles (which I know will get worse when I drain/refill), and is pretty faded. If I can get this season and next out of it, I'll be happy, then it's time to replace anyway. Water here is cheap, too. I'm really excited to get off to a good start with my new education about what my pool REALLY does and doesn't need.

Sounds like you are aware of all the possible pitfalls. One thing you might try is to drain and fill at the same time using a large plastic tarp to keep the new water from mixing with the old water. That would keep the pool from every being empty. You drain from the bottom and fill from the top. It has to be a big enough piece of plastic that it can extend onto the sides of your deck so that as the volume of the water increases on top, the sheet has room to sink without falling in and allowing the new and old water to mix.

I have never done this myself, but it has been discussed on the forum before. You may do a search and read some threads. Use the search feature in my signature below.

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Originally Posted by ksukris

Oh, and my liner only has a couple years left in it anyway. Has some wrinkles (which I know will get worse when I drain/refill), and is pretty faded. If I can get this season and next out of it, I'll be happy, then it's time to replace anyway. Water here is cheap, too. I'm really excited to get off to a good start with my new education about what my pool REALLY does and doesn't need.

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Your choice, of course. But I wouldn't, unless you are willing to do a liner installation in June. Old liners are notoriously brittle and susceptible to splitting.

If you really want to drain, there is a way to do a 'drain-in-place' but you'll need a tarp or pool cover that's about 10' bigger than your pool, so, for a 16x32, you'd need a 26 x 42 tarp. You could buy a new over-size winter cover, and do it with that.

Let me know if you are interested.

Why not just run a high CYA pool until you replace the liner? Who knows, you might like adding chlorine only occasionally.

Well I drained, refilled, and have been holding water for 36 hours, so I hope that means it was successful. I worked very quickly, left about 18" of water in the deep end to hold the liner down and immediately started refilling with three hoses pumping water into the pool, got it filled back up in about 24 hours. Added bleach as I went, as the little bit of old water that got mixed with the fresh was pretty nasty. I untucked the liner at the point where the shallow end starts getting deep, and tucked the hose from my shop vac in there to help hold the liner until water reached about 4" in the shallow end. Funny thing is, about 3 years ago, we didn't close properly and decided to drain/refill but didn't know any better that it could ruin a vinyl liner, that's when I got a couple wrinkles in the shallow end. This time, working quick and using the shop vac, I was able to drain/refill without adding any more wrinkles. I know that may have just been dumb luck on my part. I do appreciate your advice and took the warnings seriously, but I really wanted to get off to a fresh start after discovering this forum. From now on, I'm not putting anything in my pool unless I know exactly what it is and what it will do!!

Oh, and the little bit of green that was left from the old water quickly disappeared, water is blue, a little cloudy (can see bottom of shallow end but not deep end), but overall MUCH better. My test results this morning showed my FC and TC right at 8.0 ppm, ph 7.8, TA 80, and CYA at 30. I'm using my remaining trichlor pucks from the pool store until CYA gets to about 50, then it's all BBB from here on out. The cloudiness seems to be improving, but I've got a skimmer sock in there to help anyway. I've been reading lots of other threads on here over the past week, and feel like I have a better understanding of pool chemistry and operations, but I'm sure I'll be back with more questions over the summer. So glad I don't have to go back to the pool store and empty my wallet again!!!

Sounds like you're moving toward a good pool summer!