Help me get my pool back! Green with algae or ?

[Josh_U]

Hello All,

I've found these forums back in 2004 when we first purchased this house and became pool owners. I've always followed the BBB method and it's worked great... until now. Our pool has been green for weeks now and I'm at a total loss for what to do next. Here's some details:
CYA: over 100 to the best of my knowledge
TC: 30ppm
pH: 7.5
In ground, gunite ~25K gallons
Cartridge filters

I don't know if the green stuff is algae or something else. It's seems to be a very fine bright green dust when I brush it off the steps etc.. We have an aquabot and as far as I can tell, it's going right thru the aquabot bag and back into the pool.
Any help is appreciated. Thanks!

Josh

[Watermom]

Are you maintaining that high cl level without letting it yo-yo up and down? How did your CYA get so high? Trichlor pucks or dichlor shock? At any rate, if you are still using any one of those products, you need to stop. Your CYA may actually be WAY over 100 since the test cannot differentiate higher than 100. If you can sustain the high cl reading consistently, it should clear. Test and add bleach as many times per day as you can. There is no such thing as testing and adding bleach too often when you are trying to clear a pool. Have you cleaned your cartridge any time recently?

[Josh_U]

The pool originally was chlorinated with an automatic feeder using trichlor pucks by the previous owner. I also used the feeder until it broke and I learned the ways advocated by this forum. It's been a few years since I checked the CYA but even back then it was 100+. Also, I've gone back and forth on using pucks in a floater in addition to bleach but I guess I should stop that?
With this green outbreak, I have been checking cl daily and keeping it at 30ppm. I cleaned the cartridges a few weeks ago, pool was already green at that point. They are the original cartridges (10 yrs old) but have been well taken care of.
It doesn't seem like the filter or pool vac are getting rid of anything. Will it just magically clear up over time? Should I do a partial drain to try and lower the cya?
Thanks for your help!

[aylad]

This isn't going to clear up by itself, it's going to take some persistence and patience (and lots of bleach) on your part. You are doing the right thing to keep the chlorine up, but you really need a current CYA level to know how high to take the chlorine. What that CYA level is will also determine whther or not you should consider draining some water.

The chlorine you're adding to the pool will kill the algae, but the filter is what gets the dead algae out, so it must be working in order toclear up the pool. Do you see particles returning to the pool through the returns? If so, you will need to replace the cartridge.

Janet

[Watermom]

If the CYA was 100+ a few years ago and you have continued to use trichlor pucks, your CYA must be through the roof! You can do a partial drain and refill and try and lower it. Depending on how high that CYA actually is, it is hard to tell what it will be after you drain some. It might take a couple of partial drains and refills to get it to a more manageable level. You can probably drain 2/3 of it at at time. You might try using Poconos' plastic sheet method for draining where you lay a large piece of thick plastic on the top of the pool and simultaneously drain from the bottom as you fill on the top. This might actually be a good idea since it would essentially allow you to completely drain this pool without fear of it popping out of the ground. I'm going to ask Al (Poconos) to come and talk to you about this further.

[Poconos]

Josh, welcome to the forum.
I've never done the plastic sheet thing but it would be the most efficient and safe way to dilute water. Trick is to get a big enough sheet to keep the top and bottom layers from mixing. You would drain from the bottom and fill the top layer and let the sheet sink during the process. You could virtually do a complete water change without risk of popping the pool. I don't know what might be the best way to stick smaller sheets together. Possibly layers of duct tape may hold long enough. As for the CYA testing, you could dilute a sample to get it in range of the test. ex: 1 part distilled or tap water (no CYA) to 1 part pool water, double the reading. 2:1 triple etc.
Al

[Josh_U]

Really appreciate the responses. I do notice little bits of stuff coming back thru the return jets. It's actually 4 very large cartridges and I'm scared to find out how much replacement is going to cost. On draining, will I need a submersible pump to get the water out?

[aylad]

I think so, unless you have a bottom drain.

Janet

[PoolDoc]

The sheet drain method is tricky -- I need to get with Al and work up a guide to doing that, step by step. Do it wrong, and you can end up wasting a lot of water. Meanwhile:

#1 - Get a FAS-DPD testkit, if you don't have one, ASAP. Amazon link in my sig (wait a day, if the Amazon seller isn't "Amato Ind", other sellers sometimes ship the wrong kit.)

#2 - Buy some sodium bromide pool treatment:
http://www.intheswim.com/Pool-Chemic...ems-Algaecide/
and add a dose -- that will quickly create a free bromine residual that will kill algae. But it will increase your chlorine consumption, because bromine cannot be stabilized. Add 1/2 label dose, and wait 24 hours. Finish the does if the 1/2 dose is not enough.

#3 - Get a CHEAP OTO & phenol red test kit, and maintain DARK YELLOW chlorine levels.

#4 - Once you get the Taylor kit, maintain 10 ppm + the bromide.

. . . more later.

Ben

[Josh_U]

Yeah, the plastic sheet method sounds like a nightmare (appreciate the idea though).
Right now I only have the FAS DPD powder/ titrating reagent for checking and keeping the cl at 30. Are you saying once I add the bromine, to let the cl drop to 10?
This is the worst the pool has ever been in 7 years of ownership. Could part of it be that our filters are simply old and no longer performing even though they've recently been cleaned?