Drain first or SLAM

[PoolStored]

Should the drop in ppm be getting less each 2 hour period when SLAMming or does UV/sunlight also play a role so might not get less during peak sunlight times?

Can be variable with UV. A consistent overnight chlorine loss test, 1.5-2.5 can be hidden algae in weirs, drains etc.

 

[pgjohnson]

If I keep at the SLAM is that hidden algae killed or does it need to be found/brushed.

 

[PoolStored]

If I keep at the SLAM is that hidden algae killed or does it need to be found/brushed.

Algae creates a biofilm. It is impervious to chlorine, unless you can break the biofilm.

Algae needs sunlight to grow. In my case it was likely bacteria that was hidden in my ladder tube....

3.jpg

• PoolStored
• Aug 2, 2022

Something is hiding somewhere....

 

[pgjohnson]

Could it be iron in the water, have had issues with very light (barely visible) iron staining before and have done a AA treatment back in June. Can see light (barely visible) staining starting again.

 

[pgjohnson]

Found some algae in the hydrostatic valve drain. Have tried everything but no way to remove cover, have broken some of it. Used toothbrush to try brush some out, not many options

Due to not being able to get the cover off, made a makeshift vacuum out of pool hose, funnel and hosepipe (which could fit through the broken parts i made in cover) and along with toothbrush and screwdriver managed to clean the inside of the drain. Now it looks very clean (after 2 hours diving up and down) but I guess I will not know if I got 100% of everything, definitely can't see anything significantly left in drain (no green). Then dove down with tube and dropped some liquid chlorine directly into drain.

Hoping all this effort shows some improvement in the results. Did 1 hour cleaning at lunch (ended at 2pm) and a second hour later after 4pm but between 2pm and 5pm did not get a big drop in FC, not sure its related to my cleaning of less sun on the pool. Actually probably not related as disturbing it should have used more chlorine and only did vacuuming at 4pm.

Can this small amount of algae cause the OCLT to drop by 2ppm?

Thanks for all the patience and help so far.

 

[dereksanders]

Yes. UV always plays a role in FC degradation so that has to be taken into effect. It’s hard to say with any degree of certainty what the exact loss is by UV and nasties.

If you have no visible algae but are still experiencing FC loss overnight that means the algae is hiding somewhere. You have to find it and eradicate it. You found it.

 

[pgjohnson]

Ok so unless I am imaging things I had some success.

Measured at 9:05pm last night - 15.5ppm
Measured at 5:43am this morning - 15ppm (CC 0) - sun had been up an hour earlier but overcast.

1. Did have some heavy rain and lightning last night but would presume the rain would dilute/lower the chlorine reading anyway?
2. Can the small amount of algae i found in the drain affect the whole pool and cause the past nights (and nights before that hovering around 1.5/2) 2ppm drop?

Think I will continue today just to make sure.

 

[PoolStored]

1. Did have some heavy rain and lightning last night but would presume the rain would dilute/lower the chlorine reading anyway?

Not much.

2. Can the small amount of algae i found in the drain affect the whole pool and cause the past nights (and nights before that hovering around 1.5/2) 2ppm drop?

Yes, see the picture above from by ladder. OCLT was 1.5-2.0 loss for two nights until I cleaned the inside of the ladder. Poof! Passed.

Think I will continue today just to make sure.

Good choice.

 

[pgjohnson]

As I said will retest tonight so following the SLAM procedure again today.

CYA - 30 - 40
Just concerned as losing like 4ppm every 2.5 hours but it is an extremely hot day (34 degrees Celsius, UV 10.8) and pool in full sun. Does FC drop quicker when at SLAM levels?

 

[Texas Splash]

Does FC drop quicker when at SLAM levels?

It can based on two things - amount of organics in the water and CYA level. In the peak of summer, a CYA of 30-40 won't protect the FC much in hot parts of the country, so you can only imagine what it would be like with algae as well. But with a higher CYA comes the high SLAM FC level which is why we try to keep the CYA lower to save on chlorine. But that might require more frequent additions of chlorine to maintain the required FC level.

There's the other scenario where someone might over-shoot their SLAM FC level by way too much. For example, someone's SLAM level is 12, but they mistakenly go to something like 30. Then they can see a very rapid decline in FC.

 

[pgjohnson]

Thanks again. Unfortunately my OCLT last night was 2ppm. Found some duck droppings in pool and other dirt, not sure if that would affect. Also I have run out of my chlorine test kit and the new order will only hopefully arrive tomorrow. Along with sun rising around 4:30am and pump noise issues (when i can run it) I must say I am battling.

Not sure what my next step will be. Can a pool survive with a slightly failed OCLT?

Will try add chlorine at similar intervals to past days to try maintain until test kit arrives. But then would I need to start from scratch and drop PH level? And not sure how I can ever get around not having pump running at night and sun rising earlier and earlier, 4:30am this morning.

No areas I can see with visible algae - pool has 2 led lights, return pipes and drain so very simple. Drain cover not able to remove but have cleaned out as best as I can (looks clean) and dropped some chlorine directly into it.

Any suggestions very much appreciated.

 

[Texas Splash]

You mentioned not being able to remove the main drain cover right now. What are those two things on the deep end wall? Are those the lights? If so, they look different than the typical LED light I'm used to seeing. Do those covers come off by chance?

 

[pgjohnson]

Those are unused return pipes for a future heater if required. I removed the covers and cleaned thoroughly and put vacuum on pipe and sucked out stones etc. Have also just dived down (5 minutes ago) with 500ml of chlorine and tried to drop into drain but had chlorine in bottle so suction made it hard to come out but squeezed bottle so think got most to come out around drain cover. Before doing this looked carefully in drain and was fairly clean (no green) with just slight stain/dirt marks but nothing major. Yesterday did try brush around inside drain with toothbrush.

 

[pgjohnson]

Pool photos

Also uses makeshift hose to vacuum out stuff inside drain.

Just not sure what to do not being able to test until, new kit arrives - hopefully Thursday but could be as late as Monday

1. Add chlorine at similar intervals as past days and hope for the best
2. let chlorine go down and restart along with reducing PH?
3. Will I ever be successful with limitations on running pump before sunrise?

 

[Texas Splash]

I would stick to option 1. Don't let the FC fall too low which could negate all your previous work.

 

[pgjohnson]

Thank you.

Will also try run pump on low all night (and see if I get backlash from neighbors).

Should the OCLT improve each night to see results or can it stay at like 2ppm for multiple nights then get less once the SLAM levels have finally killed all the algae? So can you keep the correct SLAM level say for 3 days and only then does the algae die and the OCLT passes or is it more that multiple days mean you are not finding some algae in the pool?

I feel my drain is now clean and have tried to pour chlorine directly in but any other suggestions with not being able to remove cover? Not really sure what is meant by clean (cant see any algae like before) and how I can make sure its not the issue and this continues for weeks.

Thanks

 

[Texas Splash]

Should the OCLT improve each night to see results or can it stay at like 2ppm for multiple nights then get less once the SLAM levels have finally killed all the algae?

Typically the OCLT is the very last test of the 3 SLAM criteria to be performed. That means the CC reading is usually very low (0.5 or less) and the water is pretty-much crystal clear. Naturally no visible signs of algae. At that point the OCLT is the final step. There's no sense doing the OCLT is the other two criteria didn't pass. If the water testing is consistent and accurate, the OCLT is a good indicator of your water condition. If there is a drop of more than 1 ppm of FC in the hours of darkness, there is too much organic activity in the pool somewhere. It's just that simple since the sun's UV rays are taken out of the FC loss equation.

With a pool as simple as yours, with very little accessories in the water, we should be able to pin this thing down. Algae simply cannot survive is a properly chlorinated (especially elevated FC) body of water as long as there isn't a place tucked away where algae could be undisturbed protected by its own type of biofilm.

 

[PoolStored]

Should the OCLT improve each night to see results or can it stay at like 2ppm for multiple nights then get less once the SLAM levels have finally killed all the algae? So can you keep the correct SLAM level say for 3 days and only then does the algae die and the OCLT passes or is it more that multiple days mean you are not finding some algae in the pool?

I feel my drain is now clean and have tried to pour chlorine directly in but any other suggestions with not being able to remove cover? Not really sure what is meant by clean (cant see any algae like before) and how I can make sure its not the issue and this continues for weeks.

As Pat said, it can bump around. If your OCLTs are consistently 1.5-2, there is something lurking.

Mine was the inside of the ladder...it sat at 1.5 loss for 3 days until I figure out the ladder.

This cover has two plastic plugs that cover the screws. Turn the pump off, use a small flat screwdriver to pull the plugs up (9 and 3 o'clock), then remove the cover and scrub inside:


I would remove the lights and scrub behind them if you haven't.

Scrubbing is key to break the biofilm and allow the chlorine to kill the algae.

 

[pgjohnson]

Have managed to remove the cover (see pics), and scrubbed extensively, but seems very clean now. Did find algae here 2 days back.
Not sure I can get those lights off, they are well sealed to the wall.
In the unused return jet in shallow end and 2 in deep end I have put my fingers inside with cloth and also put a toothbrush inside and scrubbed around.
Cleaned skimmer box a few days back and have washed out cartridge filter twice.
Anything else I can try clean, think of?

Pool is very clear and CC is basically 0. Will add chlorine by guessing until new test kit arrives.
Thanks again for the help and patience.

 

[PoolStored]

See if there is a screw at 12 o'clock in the chrome of the lights.
Did you check the weir doors for algae?
Finally, post a picture that includes the entire pool, or multiple pictures that includes the entire pool...we only see pieces in your media...