Good test values, still occasional light algae dusting

Jump to latest Follow Reply
bware

bware

0
Platinum Supporter
Apr 7, 2015
142
The Woodlands, TX
Readings 9:30 am:
Ph 7.5
FC 5
CC 0
CH 475
TA 90
CYA 70
Salt 3450
Temp 87

I had this problem much worse back in May and SLAMMED for 4 days and cleared it up nicely. Even though my FC/CYA ratio is good, seems like this dust creeps back in , mostly in hot tub and a corner or two, when FC gets below 6 or 7.To all you chemistry majors out there, What am I missing?
 
You may not get good circulation in those areas. You can pour a little chlorine directly in the problem areas and let the SWG do the rest. Make sure you round up for the CYA level and target the top of your daily FC range.
 
woodyp said:
It's heating up, I'd run that SWCG a bit higher. Sounds like you're still killing a little something though. Have you passed an OCLT test
Click to expand...
No I haven’t done OCLT test yet but I’ve had the SWCG turned up to 85 % for several days and that’s the highest I’ve run it ever and it’s just a little over a year old. Makes senses there’s something being killed but never get any CC.
when FC was still coming down from SLAM in the Spring, nothing showed till it got below 7 which was just a few weeks ago.
 
bware said:
No I haven’t done OCLT test yet but I’ve had the SWCG turned up to 85 % for several days and that’s the highest I’ve run it ever and it’s just a little over a year old. Makes senses there’s something being killed but never get any CC.
when FC was still coming down from SLAM in the Spring, nothing showed till it got below 7 which was just a few weeks ago.
Click to expand...
You probably have something brewing.
Run an OCLT with the SWG off.
The longer you wait on this, the more work it will be later…
 
bware said:
I’ll run OCLT tonight. Since not SLAMMING, should I still run pump thru night or just 30 mins before morning FC test?
Click to expand...
I would turn the SWG off, keep the pump running all night, test 30 minutes after you turn the SWG off, and then again in the morning before the sun hits the water.

Overnight Chlorine Loss Test
 
Ok, ran the OCLT overnight and lost only 1.0 FC from 7 to 6. Guess I’ll add a little bleach bleach and bump it up a little. Still am puzzled as to why having SWG at 85% and FC 5 to 7 and still fighting with algae dust. As I said before, biggest accumulation is in the hot tub. I’ll keep brushing walls and testing regularly. Any other thoughts are appreciated. Thanks!
 
With the hot tub jets off and just normal pool returns on, put a couple of small, lightweight floating toys, ping pong balls, or tennis balls in the hot tub and watch to see how much they move. If you don't see much movement you may not have good circulation in that area. You can also pull a water sample from the hot tub and see if it tests lower in FC than the bulk water in the pool.
 

Enjoying this content?

Support TFP with a donation.

Give Support
bware said:
Ok, ran the OCLT overnight and lost only 1.0 FC from 7 to 6. Guess I’ll add a little bleach bleach and bump it up a little. Still am puzzled as to why having SWG at 85% and FC 5 to 7 and still fighting with algae dust. As I said before, biggest accumulation is in the hot tub. I’ll keep brushing walls and testing regularly. Any other thoughts are appreciated. Thanks!
Click to expand...
Forgive me if this has been addressed above - but how old is your SWG? What has your CSI been typically? Any scale ever identified on your SWG?
 
zea3 said:
With the hot tub jets off and just normal pool returns on, put a couple of small, lightweight floating toys, ping pong balls, or tennis balls in the hot tub and watch to see how much they move. If you don't see much movement you may not have good circulation in that area. You can also pull a water sample from the hot tub and see if it tests lower in FC than the bulk water in the pool.
Click to expand...
Good ideas. I’ll pull sample and check.
 
A few things for AFTER your SLAM.

What is your pump schedule? I see you have a 2 HP pump and I'm assuming it is a single speed. How many hours a day do you run?
Your SWG is running at 85%, with the FC at 5 ppm in the morning, I'd guess you are not making enough chlorine. You may need to increase your SWG % or run the pump longer. You should be near the top of the FC range in the morning.

In the LONGER term, you may wish to switch the pump to a Variable Speed. You will save money, a lot of money. And you can run the pump 24/7 with the SWG at a lower level. I run my pump low speed 20 hours a day and a high speed 4 hours a day (6-8A and 4-6PM), for the skimmers. My SWG for 25K gal pool is 38%.

A 2HP pump uses ~3000 Watts of power. My Variable speed pump uses about 80 Watts 20 hours a day and 800 Watts 4 hours a day. If you run 8 hours a day, the savings could be ~$700 per year. If you run more, the savings will be even more.
 
  • Like
Reactions: reggiehammond
bware said:
seems like this dust creeps back in , mostly in hot tub and a corner or two
Click to expand...
I'm in the Houston area too, and in addition to following TFT "chemistry" practices, we're running our variable speed pump slowly during all sunshine hours (or at least during the 9 warmer months of the year). If you are not doing this already, it might be worth a try.

I see you have a hot tub too, and keeping the water moving in hot, Texas, hot tubs helps our pools in several ways. I did not invent any of this; I'm simply mentioning things that I picked up from various TFP forum posts that stuck with me:
1) the sun "eats" chlorine much more aggressively in shallow water, so "rolling" the Jacuzzi water helps keep that mostly shallow water chlorinated (to same CL level as the rest of the pool),
2) similarly, rolling the water keeps the hot tub water cooler than if all pumps are off, and
3) circulation in general is a good thing in preventing algae.
 
red-beard said:
A few things for AFTER your SLAM.

What is your pump schedule? I see you have a 2 HP pump and I'm assuming it is a single speed. How many hours a day do you run?
Your SWG is running at 85%, with the FC at 5 ppm in the morning, I'd guess you are not making enough chlorine. You may need to increase your SWG % or run the pump longer. You should be near the top of the FC range in the morning.

In the LONGER term, you may wish to switch the pump to a Variable Speed. You will save money, a lot of money. And you can run the pump 24/7 with the SWG at a lower level. I run my pump low speed 20 hours a day and a high speed 4 hours a day (6-8A and 4-6PM), for the skimmers. My SWG for 25K gal pool is 38%.

A 2HP pump uses ~3000 Watts of power. My Variable speed pump uses about 80 Watts 20 hours a day and 800 Watts 4 hours a day. If you run 8 hours a day, the savings could be ~$700 per year. If you run more, the savings will be even more.
Click to expand...
Yes, it is single speed and just replaced it after it went south during the freeze in Feb. I have always run pump during hours of direct sun exposure (10-4) and have never in 15 yrs set SWG higher than 60%. Different times I guess. I’m setting to run 10-6 now and see what happens. Maybe more brushing in hot tub for sure.
thanks for your input!
 
EngineerNerd said:
I'm in the Houston area too, and in addition to following TFT "chemistry" practices, we're running our variable speed pump slowly during all sunshine hours (or at least during the 9 warmer months of the year). If you are not doing this already, it might be worth a try.

I see you have a hot tub too, and keeping the water moving in hot, Texas, hot tubs helps our pools in several ways. I did not invent any of this; I'm simply mentioning things that I picked up from various TFP forum posts that stuck with me:
1) the sun "eats" chlorine much more aggressively in shallow water, so "rolling" the Jacuzzi water helps keep that mostly shallow water chlorinated (to same CL level as the rest of the pool),
2) similarly, rolling the water keeps the hot tub water cooler than if all pumps are off, and
3) circulation in general is a good thing in preventing algae.
Click to expand...
As I replied to red, I just replaced the pump in Feb. when you say “roll” the water in hot tub, it is circulating all the time pool pump is running. Do you mean running the blower? I rarely use the hot tub especially when this hot. Guess reason this is so puzzling is I’ve never had this happen in the 15 years I’ve had the pool.
 
I'm also in the Houston area (Energy Corridor). Using your pool size 15,500 gallons, 6 pump run hours and SWG, at 60% you generate 1.6 ppm of FC a day. There is a function in pool math in the "adding chemicals" which allows you see how much chlorine you are adding.
At 70 ppm CYA in Houston, I will say that is not quite enough.
At 8 run hours, you will get about 2.2 ppm FC. That is closer to what I run.
It has been very very sunny recently, since the June/July rain stopped. I think the extra 2 hours a day will help. I think setting the SWG to 75% will also help. That will give you a boost of 2.7 ppm FC a day.
My other suggestion is to try to be closer to the upper end of the FC range. The FC range is 3-10 ppm with the "target" of 5.
I setup my pool to be around 8.5-9 in the morning on a sunny day, so that I'm still in the range at the end of the day. You are running the SWG hard during the sunny part of the day, which is good. But you may want to boost your FC so that you start the morning around 8 ppm. You can get the FC up by extending your pump hours for a few hours for a few days.
 
bware said:
when you say “roll” the water in hot tub, it is circulating all the time pool pump is running. Do you mean running the blower? I rarely use the hot tub especially when this hot.
Click to expand...
Sorry this was so confusing, and I definitely did not mean to run your blower! It sounds like you are already circulating you hot tub water whenever the pump is running. We run our pump continuously during daylight hours at 30 GPM. We are draining from pool skimmer and hot tub drain and returning water to both the pool and the hot tub. So, our hot tub water is never just sitting still now during daylight hours.
 

Enjoying this content?

Support TFP with a donation.

Give Support
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply