Big SWG pool with algae, shocking with clor-brite

[Dagobah]

So I've got a large (35k/gal) pool with an algae problem here in Texas. Have dealt with it before by using my local pool store's advice and shocking with Chlor-brite. I just finished their shock regiment, but not seeing the same results. After some digging, found a lot of people recommending I stay far away from using chlor-brite as it raises CYA. Wondering what I should do... here's my stats before shocking:

FAC 0
TAC 0
Salt 3200
CH 200
CYA 40
TA 160
pH 8.2
Acid Demand 5
Pho 200

What I've done since:
-The lack of any FC alarmed me, and I first cleaned my SWG using 4 parts water to 1 part muriatic acid. It had been a year since I've done this.
-I added 1qt 24oz of muriatic acid first to drop the TA.
-Then waited 6 hours until the evening to shock the pool. I then added 4lbs 11 oz of chlor brite and swept the pool. I repeated this process 12 hours later, and again another 12 hours later for three doses. The last dose was added tonight, and while sweeping the pool, I was still seeing large patches of green coming of the walls and floor.

Previously I've never tested for FC or CYA, but just pH and TA. After reading here, I purchased a FAS-DPD kit, but it hasn't arrived yet-- So I'm assuming my CYA levels are limiting the effectiveness of the chlor-brite.

Wondering how I should proceed from here?

Sounds like liquid bleach is a better shock alternative. Should I go get tested again then use the pool calc to determine how much bleach to add?

What about the lack of FC to begin with. Should I be concerned my SWG isn't working properly?

Thanks in advance for helping this n00b.

 

[UN1017]

First of all, welcome to TFP.

You have a lot of things that need to be addressed, some of which you are already aware of.

• 1. DO NOT add anymore Chlor Brite. That is dichlor and the 225 oz. you've added has just pushed your CYA up by over 24 ppm.

• 2. Read pool school.

• 3. Read pool school again focusing on the shock process and the chlorine/CYA relationship.

• 4. Stay out of the pool store. Based on your "shock" of choice it sounds like you went to the place that begins with the letter "L"

• 5. You stated you ordered a FAS-DPD test kit. That is only a portion of the kits recommended. Does that mean you got a TF-100 or a K-2006? As CYA level goes, the pool store results cannot be trusted. You need some good test results from YOUR kit.

• 6. Your SWG may not be working or it could be overwhelmed and cannot keep up. What SWG brand/model are you using? Is there a reason that it may be failing? (e.g. old, throwing an error code/light) Based on "green" stuff coming off walls and floor you clearly have an algae outbreak. An SWG is not designed for battling that.

• 7. Yes, liquid bleach is the recommended chlorinator but until you know your actual CYA level it will be an uphill battle and a waste of bleach.

If I was a betting man....your CYA level is probably higher than the 40 (pool store) plus the 24 you just added. What does that mean? You really need some reliable test results before we can proceed. I'm sure a lot of feedback will be coming your way.

 

[Isaac-1]

UN1017 did a good job of hitting the high points, the only thing I want to add is once you get a reliable CYA test result, I strongly suspect you will need to do a partial water replacement to get it back down to manageable levels, exactly how much will depend on exactly how high the CYA really is. If the current numbers are right at 40+24 ppm CYA approximately you are in the general suggested zone for SWG operation, however it will make shocking more difficult.

Ike

 

[Dagobah]

Sounds worse than I expected Have never had to do water replacement before, let's hope I don't.

Some answers:

• 
  Yes, been reading pool school a LOT. It's mainly why I decided to post here. Got very concerned after I added all that Chlor-brite to the pool....Want to make sure I adress it correctly. And as suspected, the pool still has hints of algae this morning.
  
  Yes, it was Leslies. Won't be going back.
  
  I purchased the K-2006 kit from Amazon. Should be here today through Thursday.
  
  My SWG is a T-CELL-15. Googling tells me it's a Goldline. I use this with an Aquarite controller. It was throwing a inspect cell light, but from what I understand, that trips every so many hours and hadn't been reset last time.

And a few questions:

• 
  1. Until I have my kit, should I just let the pool run as normal and stay out of it?
  
  2. Isaac-1 mentioned and I read it elsewhere here about the normal CYA range for a SWG being quite a bit higher than a chlorine pool. If that's the case, is the thinking that if you maintain levels, you just shouldn't have to shock, or you should expect to have a hard time doing it each time? I guess those two things seem at odd to me: higher suggested CYA for a SWG, but that also resulting in a difficult shocking process.
  
  3. How can I determine if my SWG is in need of replacement? Is there a way to tell how old it is? We purchased the house ~4 years ago. The previous owners had recently redone the pool, I'd assume this was apart of it.
  
  4. Anyone want a half bucket of Chlor-Brite?! :grrrr:

 

[Dagobah]

Just got an update from Amazon. Sounds like it could be until next Tuesday before I receive my new kit. Do any local stores usually carry these kits that I could just purchase now? Would rather take care of this sooner than later....

 

[Isaac-1]

Ok, first off around here we consider shocking to be done only in case of algae outbreak, not just for the fun of it as pool stores will tell you to do, many members go years between incidents that require shocking (storms putting debris in the pool, etc.). So when it comes to the higher CYA/FC ratio for SWG pools while yes it does make shocking harder, SWG pools if operating correctly should maintain more stable FC levels than manually dosed pools with less chance of having the FC dip below the level where algae starts to grow. This brings up another point SWG pools are Chlorine pools, they just use a salt water chlorine generator to make the chlorine on the spot, I suspect you know this, but it is an important concept.

As to finding the K-2006 in stock somewhere, being in the DFW metro area you stand a chance, it seems like there is a member here that has mentioned buying a K-2006 locally in the Dallas area, I think from Leslies Commerical spool supply store there, not the standard Leslies residential store, I do recall for certain that it was a commercial pool supply place, just not sure if it was Leslies, but I think it was. If you find one just don't let them sell you a K-2005 and tell you it is the same thing, it is NOT, check the box for yourself, we have had members try to buy K-2006 from pool stores, being told yes that is what it was, and get home just to find they have bought a K-2005.

Ike

p.s. PoolPlaza.com shows it as available they are in DFW area, may be worth checking as well

 

[Dagobah]

Thanks for the info. Looks like my kit shipped, however from what I can tell the kits are non-returnable, so I may just have to wait. I'm seeing this message on amazon:

For safety reasons, items that are classified as hazardous materials or use flammable liquids or gases cannot be returned to Amazon.com. Customers should dispose of hazardous materials according to Local, State and Federal regulations. Customers should contact their local government or local waste company for directions on how to dispose of Household Hazardous Waste.

I think in the mean time I'm just going to try and determine if my SWG is still functioning properly.

 

[Dagobah]

Had my salt cell and water tested just now at Leslies. Cell shows as bad, which could explain the issue in the first place. Some interesting readings on the water:

FC 5
CYA 45-50
TA 110
PH 7.6
Pho 0

He mentioned the phosphates could be at 0 due to bleaching. At this point something appears to be awry with the CYA vs what I expected after all the Chlor brite.

 

[Casey]

Best thing to do is wait for your test kit. You won't regret that purchase!!!

 

[Dagobah]

Agreed. I've purchased a new SWG off amazon as well. Will just keep brushing and running the pool as normal in the mean time. It has rained during the shock process, so perhaps that brought down the CYA, but I still doubt their number. Will see when the test kit arrives.

 

[UN1017]

Had my salt cell and water tested just now at Leslies.

Hey.....I thought we told you to stay out of the pool store..

You sure move quick. Just to let you know, you current cell is undersized for your pool. You need one rated for at least 60K. Did you get an exact replacement? A SWG rated for 40k installed on a 35k pool is going to have to work pretty hard.

 

[Dagobah]

Hey.....I thought we told you to stay out of the pool store..

You sure move quick. Just to let you know, you current cell is undersized for your pool. You need one rated for at least 60K. Did you get an exact replacement? A SWG rated for 40k installed on a 35k pool is going to have to work pretty hard.

Ha. Well, I did a decent bit of searching on the forum as for the best way to determine if the cell was dead. Found a handful of threads suggesting the store rig is the best way to determine this. Is there an alternate method I missed? As for moving fast, I want to get the pool back in order asap. With 95 degree days, it's going to just get worse the longer I wait.

Yes, went with a direct replacement. I didn't see any larger options on Goldline's site that work with the Aquarite. I was typically using a setting of 50% output on the aquarite with the 40k rated cell.

As far as the pool test, without having my kit in hand yet, figured it'd be interesting to see where the pool store numbers were. Especially once I can compare when my own kit arrives. (I'm still waiting on my kit before doing anything else though.)

 

[Dagobah]

I'm back...

So my test kit came in. CYA wasn't as high as expected, but could use some help understating some of the other levels.

FC 15
CYA 90
TA 150
pH 7.8

FC: I initially guessed my new SWG was working much more efficiently than my old one, so I reduced the % from 70 to 40. This was two days ago, doesn't seem to have helped... what's going on here? Is it residual shock from last week?

For pH and TA, I've added muratic acid to drop the pH to 7.2 and begun aerating with fountains to bring the TA down.

For the CYA, water replacement is expensive here. Hoping I can let this just gradually decline over the summer...

 

[CUTiger78]

CYA won't dissipate over the summer. The only effective way to get it out is to replace the water.

You can cope with a high CYA by keeping your FC level high, probably around 10ppm, and that might be cost effective w/ a SWG. If you were using bleach, you might want to do a cost comparison comparing the cost of water versus the cost of the additional bleach needed to keep the FC @ 10ppm v. 3ppm at a much lower CYA level.

Good luck!

 

[Dagobah]

CYA won't dissipate over the summer. The only effective way to get it out is to replace the water.

You're right. I was referring to the gradual decline of CYA I've typically seen over the summer due to evaporation and other water losses. I've always relied on Leslies tests before, but in years past it seems to significantly drop over the summer.

So it's actually not as expensive as I expected to replace the water.

Pool calc is telling me I'd need to replace 25% of my water to get a CYA of 75
I'd probably end up paying $4.9 per 1/k gallon. If I wanted to replace 25% of the water, that'd be ~9k gal. That'd be a little over $45. Worth it, or rather let it evaporate?

 

[UN1017]

A CYA a level of 90 is not too far out of the range for a SWG pool. You may get a decrease from splash out but evaporation will have no effect. When the water evaporates the CYA stays in the pool. Your past experience with decreasing levels is probably due to three things:

1. splash out
2. overflow due to rain etc.
3. inaccurate testing at pool store

My vote is on #3.

You have to physically remove the right amount of existing water from the pool and refill it with water that does not have CYA in it.

 

[Dagobah]

Replaced 25% of the water last night. Checked it about an hour ago, and CYA has come down within range!

FC 7.5
pH 7.8
TA 150
CH 200
CYA 60-70

Now just need to get my pH and TA in check, and monitor my FC levels while I dial in the new SWG. I'll also be checking my salt level later on today.

 

[UN1017]

Excellent! Since you are using a SWG you should have no problem knocking that TA down. Also it looks like you are on the low end for CH with Diamond Brite. They recommend 200-400 and the consensus around here is 250-350. A little bump wouldn't hurt. No rush though.

Get everything dialed in then fine tune later.