I messed up!! Need help testing for algae

[matt444]

Hey everyone! I've read through the Pool School, and the sticky above, but not until after I overreacted to a green pool. My pump quit working last weekend, and it got replaced under warranty yesterday. I skimmed out everything I could see last night, backwashed, and added DE to the filter, and then proceeded to slowly add 8 gallons of 10% liquid chlorine from Home Depot. I then brushed the pool completely, and have backwashed a few times as necessary.

I knew there was no chlorine in the pool, but I completely forgot to get test results for CYA, pH, etc, BEFORE adding all that chlorine. Now that my chlorine is off the charts of my OTO drop test kit, I am going to get a FAS-DPD kit. The problem is, how do I get a reliable pH test result, now that I already added all that chlorine. I also realize (after using the pool calc website), I put WAY too much chlorine in my 13,000 gallon pool, especially if my CYA is zero (which I'm not sure about).

Bottom line is, do I need to wait until my chlorine drops down to a normal level, before I can get an accurate test done for CYA & pH? Also, will the chlorine even kill the algae, if my pH is way too high right now?

Thanks in advance for any help. The kids really want to get in the pool! The forecast calls for 100 - 110 over the next week here in Gilbert, AZ!!

Matt

 

[tim5055]

With FC above 10 you are not going to get an accurate pH. With a swamp, the FC is going to drop quickly. Plus, you really don't want to keep adding massive amounts of chlorine until you have an accurate CYA and a method to test FC above 5.

 

[Texas Splash]

Sounds like you should just let the FC come down a bit while you wait for the proper test kit. Once the FC is back to earth, adjust and keep your PH at 7.2 in preparation for a "SLAM". While waiting, you can stock-up on liquid bleach and re-read the SLAM info (link below) so you are clear about the "MAINTAIN" and 3 items required to pass SLAM. When your kit arrives, get that good CYA reading and match it-up to your SLAM FC requirement based on the CYA by looking at the Chlorine/CYA chart (link below). Then you'll be on your way!

 

[matt444]

Thanks so much for the quick responses! This site is awesome!!

I have an extremely busy schedule next week, so I decided to spend more than I wanted to for a test kit. I went to a couple local pool stores, and they don't stock a kit that does FAS-DPD method for chlorine. Luckily, one of the employees heard me talking to his co-worker, and he happened to have special ordered a Taylor K-2006 for a pool maintenance contractor. He said he would sell it to me for $35 below their list price of $105. So I bought it for $70. I know it wasn't a good deal, but sometimes you have to pay a premium when time isn't on your side, right? Anyway, below are my updated test results:

FC: 21
CC: 2.5
CYA: 100+ (see photo below)
pH: 7.8
TA: 160
CH: 320

So, if I estimate my CYA at 130, the Pool Calculator tells me to replace 69% of my pool water. After reading through the material on this site, it's obvious why my CYA levels are so high. I've been using trichlor 3" tabs in a floater every day since I bought this house last July. Also I occasionally would dump in a few cups of dichlor powder "shock" after heavy use, etc. See photos below for exact chemicals I've been using.

I went ahead and removed the chlorine tab floater for now. So, do I really have to empty out 69% of my pool water, or should I just continue to shock with liquid chlorine, but just raise the amount of chlorine that I use to get it to true shock level? With my CYA at 130, the Pool Calc says to add 224 oz. of liquid 10% chlorine, to bring my FC level up from 21 to 39 (per the Chlorine CYA chart linked in Texas Splash' signature). With the pool still pretty green, I would imagine I'll be vacuuming to waste quite a bit throughout the weekend anyway, so my CYA will drop naturally, right?

I should add that I've removed all debris from the pool, backwashed multiple times, added 4.5 lbs of DE back into the filter through the skimmer basket, and I can see the main drain in the deep end now. The pool water is definitely a lighter shade of green as well. So, I think the 8 gallons of 10% chlorine last night helped quite a bit. The pool water is moving through the pump & filter nicely now.

Thanks again for the help!
Matt

 

[matt444]

I made an executive decision, after reading a few more threads on this forum. I just added 2 gallons of 10% liquid chlorine, to bring the FC up to shock level of 39 ppm for my high CYA level. Then I brushed the entire pool (all steps, walls, and floor) to break up the algae some more, and mix up the chlorine. After we get back from dinner later, I'll vacuum to waste & record FC & CC one more time tonight. We'll see where it's at in the morning. Wish me luck!!

 

[matt444]

Got home from dinner, and the pool looked even better! I went ahead and vacuumed up the dead algae from the steps & floor, and then tested one more time for the night:

FC: 28.5
CC: 1.5
pH: 8.5ish
CYA: 130ish

I'll test again first thing tomorrow before the sunlight hits it, to see how much it drops overnight. I think I'm close at this point. Then I'll have to figure out the CYA...

 

[jblizzle]

I think your CYA is much higher than you think. The scale is logarithmic. You likely will need a few partial drains.

 

[matt444]

I think your CYA is much higher than you think. The scale is logarithmic. You likely will need a few partial drains.

I think you're right! I was wondering about high CYA, and the effects it must have on all the people that sanitize their pools the traditional way with trichlor pucks & occasional dichlor powder shock. What are the other negative aspects of high CYA, besides needing more free chlorine?

 

[jblizzle]

That is the downside. Crazy high FC levels required to clear up algae and then high FC levels for maintenance to keep the water clear. And once the FC is greater that 10ppm, the pH test is no longer valid.

 

[aussieta]

you can do a diluted cya test
take a sample of pool water
mix equal parts pool water and tap water
use this mix to fill bottle to first line
then use cya solution to second line
perform test as usual but double your final result

 

[matt444]

you can do a diluted cya test
take a sample of pool water
mix equal parts pool water and tap water
use this mix to fill bottle to first line
then use cya solution to second line
perform test as usual but double your final result

So, I woke up a bit late this morning, and didn't do the overnight test until 9am, so the pool water was partially in the sun for a couple hours. Here are the test results. I followed aussietas's instructions for a diluted CYA test:

FC: 28
CC: 1
pH: 8.2ish (invalid due to high FC)
CYA: 130ish

Now I'm not sure what to do. Is it time to partially drain/refill the pool now, to get the CYA back down to normal? Or should I put more chlorine in for one more day of shocking, and brush/vacuum the pool again? Then drain/refill after the overnight test is a success?

Here is a photo of what the pool looks like right now. I wish I would've taken a "before" photo on Friday afternoon, when it looked & smelled like a swamp!! The water is still somewhat on the green side, with a few stains on the walls & floor, but it's a bit unbelievable how quickly it got back to almost normal (thanks to this site, and the great people on here!!)

 

[Soonersalt]

Looking at your CYA test photo, I'm wondering if u are doing the test properly. Are you looking down the tube from above until the dot disappears. Should be done in a well lit room or outside. If you are actually reading 130, there is no need to wait, you need to drain. Otherwise you will continue to fight adequate chlorination.


Sent from my iPhone using Tapatalk

 

[matt444]

Looking at your CYA test photo, I'm wondering if u are doing the test properly. Are you looking down the tube from above until the dot disappears. Should be done in a well lit room or outside. If you are actually reading 130, there is no need to wait, you need to drain. Otherwise you will continue to fight adequate chlorination.


Sent from my iPhone using Tapatalk

I am looking down from above, adding drop by drop until the black dot disappears. The scale only goes up to 100. I posted the photo to give a perspective of where the water line was, relative to the 100 on the scale. After the suggestion by aussietta, I did a diluted test, and the black dot disappeared at 65, so I doubled that to come up with 130.

I know I need to drain at some point, but I just don't want to do it too early now that I've already invested 10 gallons of 10% chlorine to get it to this point. The overnight drop in FC was only .5 ppm, and my CC was at 1.0 ppm. Based on that, and my photo, would you say I'm done SLAMming, and the next step is to drain/refill to fix the CYA level?

 

[MarianParoo]

If it were me, I would do one more overnight test. Then you would be double sure.

 

[pooldv]

Good lookin pool!

 

[matt444]

If it were me, I would do one more overnight test. Then you would be double sure.

I took your advice. Here are the results at 9pm:

FC: 21.5
CC: .5

Let's see how this thing holds up for one more night. Here are a couple photos. You can see stains on the floor of the deep end.

 

[jblizzle]

The CYA test should be poured it slowly, not drop by drop, that would take forever.

 

[matt444]

The CYA test should be poured it slowly, not drop by drop, that would take forever.

After mixing the pool water with the regent (7mL each) into the dropper, I added the mixture to the small comparator tube one drop at a time, watching the black dot until it disappeared. I'm not sure what you mean by slowly pouring it in? How could it be poured from a dropper?

- - - Updated - - -

Good lookin pool!

Thanks, although the plaster is actually in bad shape. It'll need to be re-surfaced in a couple years. The stains don't show that well in the photos during the day. The water is crystal clear though, at this point. Nothing beats SLAMming with liquid chlorine!

 

[MarianParoo]

Jason knows WAY more than me...!!! But especially at high CYA, I think it's good to go drop by drop as you get close. Remember, you can pour the solution back into the squirt bottle and redo the test several times.

 

[matt444]

Here are the overnight results, 7 hours later at 4am:

FC: 20.5
CC: .5

Is the SLAM complete?