Black Stuff Stuck To Bottom

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Pharmacyman

0
LifeTime Supporter
Sep 9, 2007
59
High Point, N.C.
Pool Size
20000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Pentair iChlor 30
Hi,

We got a severe algae bloom when our sand filter control valve went out and it took two weeks to get repairs done and water flow back to the pool. We have made progress in this week using your algae treatment procedure. But with all the sweeping, backwashing, cleaning baskets and filters, and high FC levels using bleach; there is some stubborn black stuff on the pool bottom that is hard to sweep up.

Do you have any ideas that would make getting these black spots up easier?

Even though I couldn't pump and circulate water, would have sweeping the pool while waiting for service have helped to prevent this?

Thanks.
 

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Sorry, I have a TF-100 test kit:

PH = 7.4
FC = 4 ?
CC = 0 ?
TA = 40

When I added the heaping scoop of the R-0870 it did not turn as pink as in the past. Thus the reason for the "?" as I question the results. Do you think I need new reagent or could the pool water sample have caused this.

What do I need to do about the black stuff sticking to the liner? Did the algae cause this? I have had algae problems in the past and when it was dead it swept away easily. This stuff is not sweeping away easily.
 
TF-100 :goodjob: Honestly not to sure (yet) on the black sticky substance you see at the bottom. But your chemistry does confirm you need a few adjustments - perhaps it's related. For example:
- CYA not listed. Remember that is a critical number. We must to know the CYA to know what FC level you should be maintaining (see Chlorine/CYA Chart link below).
- FC not turning pink and (?) sounds like it's very low or perhaps zero (allows algae quickly)
- CC (?) - I think your CC as zero is suspect since your FC is also in question.
- Your TA is low and should be a minimum of 70 as noted on the Recommended Level chart (link below)

It is possible the black stuff is algae related, but ideally we need to confirm your CYA first to get you ready for a SLAM. I would confirm the CYA right away and prepare to do a SLAM. If you have any questions, please let us know. Others chime-in on the black sticky stuff as this thread continues.
 
Yes, just tested OTO and it is yellow. SWG has been at 100% for a week and is functioning, pump 24/7 for past week except for when cleaning, backwashing, etc. I have chlorine.

No thoughts on black stuff? From algae or what? What do I do about it?
 
Does seem odd that your SWG has been at 100% for a week yet your FC was so low as performed by your TF-100. Either something went wrong with the test, there is something not right with the SWG, or you have an algae situation tearing-up that FC (perhaps the black substance).
 
Actually I hit pool hard last weekend with bleach, sweeping, backwashing and the pool quickly turned from dark green to clearer but slightly milky looking. I need to be honest with you guys so you can help me better: I was working out of town Wednesday through Friday this week and when I checked the pool this morning I discovered that at some point the flow had slowed or stopped. So although the pump was set 24/7 the flow must have slowed or stopped at some point. I backwashed this morning and do have good flow and SWG is producing now. I just did another test and here are the results:

PH = 7.6
FC = 3.5 (still not sure here if there is no chlorine in pool or my R-0870 has gone bad...its probably 3 to 5 years old. Thoughts?)
CC = hard to determine because solution didn't really turn very pink to start with. Could not get a change, so would say zero or unknown
CYA = 0 (I could see the black dot after filling tube all the way to the top)
 
Honest is the best policy. :) 3-5 years old is a long time for reagents. That milky cloud after the initial bleach could've been algae residue from the spike in chlorine. Not sure if R-0871 is available locally, or if you have to just order on-line through TF-100 testkits.com. They are pretty quick though. Perhaps look locally for a FAS-DPD kit for now. But I suspect when you were away that your FC dropped too low to sustain the proper level. In addition, if your CYA actually is zero, then there is nothing to protect the chlorine in your pool. The CYA for a non-swg is minimum 30 - yours 60.

So I would definitely expedite getting some new reagents to ensure you can accurately check your FC and CC, At the same time, use the poolmath calculator to start increasing your CYA. If your CYA reagents is as old as the others, well, you may want to re-order that as well. :) So much boils-down to the accurate testing.
 
I'm pretty sure CYA is accurate based on testing years ago when my kit was new. Something about the water here, it has no CYA, I don't know. I will get my CYA sock in the skimmer right away and see what I can do and also get some new reagents.

Thank you Texas Splash and also pooldv. It appears I may not have enough chlorine in my pool after all, although the OTO test honestly turned yellow today. I waited awhile before reading and I noticed a color change indicating CC present in the water.

Would you please send a link or tell me where on the site I can find normal chemistry levels for my SWG pool? (never mind, found link)
 

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Below I my signature is the link to SLAM. I'll post it again though for you after this. Your CYA does not need to be 60 or 70 to SLAM. As soon as it gets close to 30 is ideal because you need "some" CYA (stabilizer) to protect the chlorine. Remember though, CYA doesn't start showing-up for a few day after it dissolves (the granular type). You can get the liquid stabilizer but I costs more. :(

- - - Updated - - -

The SLAM link is below, but here's it is in a nutshell:
SLAM is the term used when we “Shock” our pool to a higher “Level” of Free Chlorine (FC) and “Maintain” it that way until 3 objectives are met:
1. Water is clear
2. You do not lose any more than 1ppm of FC overnight (that's the OCLT)
3. CC (Combined Chlorine) is <.5
** You MUST meet ALL 3 items above to properly do a SLAM. Simply “spiking" the FC higher than normal isn't SLAMming, therefore there’s a good chance your algae will return.

To prepare for a SLAM, you should do the following:
- Adjust PH to 7.2 - 7.5; don’t worry about it after that during the SLAM
- Ideal CYA should be 30; the higher the CYA, the more bleach required
- Have a good amount of “regular” liquid bleach on-hand to keep your FC high at all times

Use the Chlorine/CYA chart (link in my sig) to bring your FC up to the proper SLAM level rating based on your current CYA and make sure it stays there (MAINTAIN) until you meet ALL 3 criteria listed above! That may take just a few days or even a week or two! That is absolutely critical for success.

At the same time, continue to run your pump 24/7. Remove any “muck” and debris, scrub all parts of your pool to expose any algae, and vacuum/clean (or backwash) filter as necessary. You may have to do this several times. It's a lot of babysitting, but with patience and consistency, you will succeed.

- - - Updated - - -

FYI - Fresh water typically has no CYA. Also, the two links below in my signature "Recommended Levels" and "Chlorine/CYA Chart" are your primary sources for levels. You will really use the Chlorine/CYA chart a lot. :)
 
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