Bought house, pool just turned green in a week

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JerseyRon

0
May 24, 2014
13
NJ
I've owned a pool in the past but had a service take care of it. Just moved to a house in NJ with a Sylvan concrete pool, About 20 years old. Got two inspections before buying the house and it got a clean bill of health. Water was crystal clear when we moved in two weeks ago. I expected to close it last week with the service but they're booked until Oct 8 so I need to do something now. The filter has been running but I didn't nothing else for two weeks and who knows what the previous owners did the couple weeks before that. This week it got a green film all over the walls. It brushes off but right now I have to figure out how best to handle the two weeks before closing. The SLAM method seems intense and a bit overwhelming and I can't tell if that's what I need if I just need to clear it before winter.

I've taken a bunch of pictures. He left me a couple test kits, strips, a box with a bunch of droppers and one small two-tube kit. I used the strips and them the big kit and came up with these numbers:

Fc-0
Tc-maybe .5 very hard to tell if it even changed colors

Ph- 7.6
TA-120
Calc- 400 (on strip it's very far on edge. On dropper test, can't get calc harness to read)
Cya- More than 100 (strip said 200 but the tube with black dot test didn't even come up halfway to 100

Guessing my big problem is all the cya. I also have to get some bleach but don't know how much.

The pool is a weird shape but the deep end (8' I think) is about 15x15 and then the shallow end (3-4') is 20x15.

Any help or suggestions are a big help. I'll add some pics of the pool and equipment and the stuff he left behind.

Actually pics won't work but I have:
-Taylor complete dpd chlorine/ph tests
-hth test strips
- ph down
- safer muriatic acid
- few tablets wrapped in plastic smell like chlorine
- filter is Hayward De
- there is a chlorinator hooked up but can't figure out how to open it to see if it's actually got anything in it.
 
Unfortunately, if you close with algae, it's likely to be that much harder to clean up in the spring. You're right that the high CYA is a significant problem. You really should SLAM, but that is difficult to do if your CYA is over 200, which is what it sounds like from your description of what you saw with the "black dot test"...

One useful first step would be to get a better read on the CYA level, using a diluted sample. See:
http://www.troublefreepool.com/threads/24188-Extended-Test-Kit-Directions
and scroll down to the CYA test instructions.

What is the current pool temperature?
 
JerseyRon said:
The SLAM method seems intense and a bit overwhelming and I can't tell if that's what I need if I just need to clear it before winter.

I've taken a bunch of pictures. He left me a couple test kits, strips, a box with a bunch of droppers and one small two-tube kit. I used the strips and them the big kit and came up with these numbers:

Fc-0
Tc-maybe .5 very hard to tell if it even changed colors

Ph- 7.6
TA-120
Calc- 400 (on strip it's very far on edge. On dropper test, can't get calc harness to read)
Cya- More than 100 (strip said 200 but the tube with black dot test didn't even come up halfway to 100

Guessing my big problem is all the cya. I also have to get some bleach but don't know how much.

-Taylor complete dpd chlorine/ph tests
-hth test strips
- ph down
- safer muriatic acid
- few tablets wrapped in plastic smell like chlorine
- filter is Hayward De
- there is a chlorinator hooked up but can't figure out how to open it to see if it's actually got anything in it.
Click to expand...
Well, the first thing you have to decide is if you are going to maintain the pool or hire a service? If you plan on using a service, just give them a call and have them clear it their way (different from ours) before they close. They may even say don't bother that they will do it in the spring.

Now, if you are going to do it we can help. But, it will take time & work on your part.

First, you have no idea how old the test kits you have are and if the reagents are still any good - you will need to pick up one of the recommended test kits. To effectively practice the TFPC methods, the FAS/DPD chlorine test (not the DPD you have - two different tests) is essential. All the kits on the list contain that test while very few other kits do. The kits sold at the pool store generally won't won't cut it, but be careful pool store employees are known to say “it's the same thing”. Generally it's not!

Bleach, 8.25% concentrated, a bottle a day until you get your test kit. It may or may not help - but it makes you feel you are doing something.

Throw the test strips away. They are not accurate.

Put the 3" chlorine tabs away. They have CYA which you don't need to be adding.

If you have "0" FC then the chlorinator is probably empty. Ignore it for now.

Now, if you have read around here much you have probably seen that not much credence is given to pool store testing, so don't bother going there. While you would think that a "professional" would be the best, unfortunately in most cases it is quite the opposite. Between employees who blindly trust the word of chemical sales representatives and high school kids working in the pool store for the summer you end up with poor results from their testing.

Start reading Pool School. Start with these:
ABCs of Water Chemistry
Recommended Pool Chemicals
How to Chlorinate Your Pool
 
Thanks for the responses. Pool temp is 70. Good question on whether or not I'll get a service but would like to at least give this a try. They don't want to close it
If it's nasty and nether do I.

Is there a way to lower my CYA directly or will that only happen as I treat the rest of the water?

I found a bottle of Spaguard oxidizer enhanced shock in the shed. It says it is 58.2% sodium dichloro-a-trianzinetrione. Should I throw some of that in to see if helps or until I get some bleach? Or just keep this for the standalone hot tub?
 
Nope, not dichlor, trichlor or any other solid form of chlorine as all except cal hypo add more CYA to the water. The ony real way to lower CYA in New Jersey is a water exchange. Some areas of the southwest have reverse osmosis services that will take it out.

If I were you I would do a diluted test. As 100 is the limit of the CYA test you have to do a diluted test to see anything above that. While the full instructions are in the Pool School, here is the short version. Mix 50% pool water with 50% tap water. Use this mixed sample as your test water. If still at a 100 you will need to dilute more. Here is a great chart by JamesW to explain dilution rates and what you multiply the results by to get an approximation of your CYA level.

Pool water......Tap or distilled water.........Multiply result by

....1...................1................................2
....1...................2................................3
....1...................4................................5
 
Is it weird he was able to keep the pool so crystal clear with such high cya? If I'm reading everything on the site correctly, cya is basically the leftover residue from chlorine tablets? So it would make sense it's this high if they've been using this type of chlorine for years, if not decades? If I'm also reading right, we can live with the high cya by increasing chlorine but I can see how it's an endless cycle. I'd think the vast majority of pool owners who don't spend time on this site would eventually have extremely high cya.
 
JerseyRon said:
Is it weird he was able to keep the pool so crystal clear with such high cya? If I'm reading everything on the site correctly, cya is basically the leftover residue from chlorine tablets? So it would make sense it's this high if they've been using this type of chlorine for years, if not decades? If I'm also reading right, we can live with the high cya by increasing chlorine but I can see how it's an endless cycle. I'd think the vast majority of pool owners who don't spend time on this site would eventually have extremely high cya.
Click to expand...
No, not really a "leftover residue", but a chemical with uses in it's own right. You can go to the pool store and buy it in liquid or granular form. Pools need it, just not too much. The level rises quicker than you would expect.

People who follow the standard pool store advice of tabs and shock can generally get away with it for a few years until they start having problems. When the problems occur the pool store will start selling them other stuff (algecides, floculant) which really doesn't solve the underlying problem too much CYA. With too much CYA the chlorine is all bound to the CYA and can not sanitize the pool. The final step in this saga form the pool store is the dreaded "chlorine lock". The pool store will tell you you have chlorine lock and the only way to fix it is to drain the water.

The real solution is what is taught here. Accurate testing and only add to your pool what it needs and what you know what the chemical is. We generally shy away from products that don't list ingredients or call them a "trade secret".

At this point you really can't live with the high CYA unless you have deep pockets. You have algae. The only way to kill algae is to get sufficient chlorine in the pool above the level that is bound to CYA. As an example, if your CYA were 100 you need to get the chlorine level up to 39ppm and hold it there for days. That takes lots of chlorine because as you add it to the pool it is consumed in the process of oxidizing the algae.

Once you have killed the algae you need so stop solid chlorine usage and switch to liquid. Many/most of us here use generic household bleach.

Again, you need to drain water to get the CYA into the 50 range then you should read the directions on SLAMing your pool in the How To section of Pool School and follow that procedure completely to the end.

I go back to your first comment "The SLAM method seems intense and a bit overwhelming and I can't tell if that's what I need if I just need to clear it before winter" - SLAMing is what it takes to clear the pool. Anything less is a band aid approach that will come back to haunt you later and worse.
 
Cool thank you so much for all this help. When you say drain the pool, do you mean fully drain it? Or just take it down a foot or two at a time and refill it with a hose and continue testing? I can't believe I thought I was buying such a great pool and it's two weeks in and it's nightmare city!
 
JerseyRon said:
Cool thank you so much for all this help. When you say drain the pool, do you mean fully drain it? Or just take it down a foot or two at a time and refill it with a hose and continue testing? I can't believe I thought I was buying such a great pool and it's two weeks in and it's nightmare city!
Click to expand...
Plug all your numbers into Pool Math (link at top of page) and it will give you how much water you need to replace. Off the top of my head, if your CYA is truly 100 then that is 50% water replacement. But remember, that is 50% at one time. If you do it in stages it will take a little more than 50% water replacement. I think you will find that in a month or so when all of this is behind you it won't be so bad. It's a learning curve and right now you feel like you are getting knocked around.

JerseyRon said:
One other question about the calcium hardness. I couldn't get a reading on that. Is that a bad sign ? Not sure what role that plays.
Click to expand...
What were you using to test it? Yes, you want your CH between 250 & 350 in a gunite/plaster pool. Less than that and the water is going to leach (dissolve) calcium out of the pool walls - not good for the pool.

- - - Updated - - -

Also, I forgot to say it would help us if you would add the following information to your signature

  • The size of your pool in gallons
  • If your pool is an AG (above ground) or IG (in ground)
  • If it's IG, tell us if it's vinyl, plaster/pebble, or fiberglass
  • The type of filter you have (sand, DE, cartridge) and, if you know, the brand and model of the filter.
  • If you know, please tell us the brand and model of the pump, and mention if is it a two speed or variable speed pump.
  • Date of pool build/install, particularly important if less then a year old.
  • What kind/model of water test kit you are using
  • Other significant accessories or options, such as a spa , SWG, or cleaner
 

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JerseyRon said:
Is it weird he was able to keep the pool so crystal clear with such high cya? If I'm reading everything on the site correctly, cya is basically the leftover residue from chlorine tablets? So it would make sense it's this high if they've been using this type of chlorine for years, if not decades? If I'm also reading right, we can live with the high cya by increasing chlorine but I can see how it's an endless cycle. I'd think the vast majority of pool owners who don't spend time on this site would eventually have extremely high cya.
Click to expand...
He was probably adding enough chlorine to keep algae from starting. Luck may have played a role also. The maintenance levels of chlorine required (at any CYA level) are always lower than the shock or SLAM levels (take a look at PoolMath, plug in various CYA numbers, and see what happens to the suggested FC levels). You're right that many pool owners end up with excessive CYA levels. Splash out, backwashing of filters, and water replacement (rain, snow) over the winter all work in the other direction by replacing some of the CYA-laden water with clean water. I even know of one pool, maintained with trichlor pucks, which has relatively low CYA thanks to a leak -- the pool owner is constantly adding water to offset the water loss -- not exactly a recommended technique.

However, a high CYA pool is like a bomb waiting to go off if you neglect it for a few weeks, as you said you did in your original post. Once you have algae established, getting rid of it requires such astronomical chlorine levels that very few people try to go down that path. For example, if your CYA were at 230 (the sort of level suggested by your preliminary round of testing), you would have to SLAM the pool with a FC level of 90. If your pool volume were (hypothetically, for a modest size in ground pool) 15,000 gallons, it would take 16 gallons of 8.25% bleach to get to that level. And then you'd have to maintain the level of FC, and also have a way to measure it regularly. None of this sounds practical or economical. This is why reducing CYA (partial drain and refill) is the first step suggested here.

It sounds as though you may be considering the drain and refill idea. As has been suggested a couple of times, you should first try to get a more accurate reading on the CYA level, starting with a diluted pool water sample.

The reason I asked about water temperature is simply that algae grows more slowly as water temperature drops. Apparently growth is minimal below 60 degrees. However, at 70 degrees the algae can still flourish and multiply, albeit not as quickly as it would at the height of summer. As tim5055 suggested, putting in a modest amount of bleach, while you decide on your plan of attack, can't hurt.

Regarding calcium, what exactly did the drop test do? You said it would not give you a reading...


Tanker said:
Did I miss something here? Your CYA with drops was less than half way to 100 but your strip is what registered high.
Click to expand...
If you recall, the scale on the CYA test vial has the high numbers (100 being the highest shown) toward the bottom of the vial. If the black dot disappeared with the water less than halfway up to the 100 mark, that would indicate CYA levels well over 100.
 
And, possibly 300 or more. I received a cya level of over 350 due to the previous owner using tricolor tabs and dichlor shock for years. It took a few months to discover how that can create an algae problem that was almost impossible fix.
 
I just recently did a drain and fill to reduce the CYA and it was well worth it. Drained and replaced about 60% of water. Glad we decided to do it now instead of closing and waiting until next season. When first taking in the info on this site it seems overwhelming so take it in steps and you'll learn as you go.

Start with getting an accurate measure of CYA and planning out your drain and fill - how much you need to drain and how much you can safely do at one time. Then do the drain and fill and get new test results to figure out the next step.

It's amazing how clear the pool water is now - no comparison to pool store "clear" water.
 
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