Exactly MD, it has no cover when I did the pool it was always open. I turned the valve at the end of it today and after one of the employees got a snake in from inside the pool to loosen whatever was in it up, quite a bit of brown green stuff came out for a few seconds when it was open. I closed it quite quick after the water was clear not to loose too much water from the pool. It was quite some pressure so whatever in it would have came out and the chlorine could mix more inside it to clean whatever is left. I plan on releasing more of it a bit at a time just to keep it fresh and chlorinated. It’s not as fancy as you explain and once open the water just runs outside into the garden below the pool. I will make a video soon and send.
Pool Chlorine Level Keeps Dropping (Please help! Incurring astronomic costs in chemicals)
- Thread starter qsch1
- Start date
Exactly MD, it has no cover when I did the pool it was always open. I turned the valve at the end of it today and after one of the employees got a snake in from inside the pool to loosen whatever was in it up, quite a bit of brown green stuff came out for a few seconds when it was open. I closed it quite quick after the water was clear not to loose too much water from the pool. It was quite some pressure so whatever in it would have came out and the chlorine could mix more inside it to clean whatever is left. I plan on releasing more of it a bit at a time just to keep it fresh and chlorinated. It’s not as fancy as you explain and once open the water just runs outside into the garden below the pool. I will make a video soon and send.
- Jun 1, 2018
- 14,109
- Pool Size
- 26000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Hopefully you got the crud out of it.
If it can function it does need a cover for safety reasons. Might be wise to just cap it /plug it & isolate it from the pool water to prevent more algae reoccurrence. You can always remove the plug/cap if you need to drain it.
Good idea I was thinking the same so shall I just put a pvc cap on it?
- Jun 1, 2018
- 14,109
- Pool Size
- 26000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Without seeing it I can’t say for sure exactly how to best accomplish that but yes.
Hey guys so I did a 20 ml sample this morning and yesterday afternoon. The sun was already out for about an hour or so this morning. I clocked 24 yesterday (after sun was gone) and 22 this morning about an hour after the sun came up early in the day. I also took pictures of the pool drain pipe which I have attached. I have everyday emptied some water out of it so it could fill up with clean chlorinated water. The inlet end of it is quite white now where it was green before. It is about 8 feet long in total.
20 or 25 ? 25 is the correct amount for the test. While the test would still repeat itself if the pool was algae free and you used the same sample for both tests, the FC would be 20% (?) off.
If you used 10ml at night at 20ml in the morning, it's not valid.
Sorry, I took 20 ml pool water and 20 ml tab rain water mixed it together in the glass bottle (the one for the other tests, not the chlorine glass), then I put a 10 ml sample from the larger amount I mixed together equally into the chlorine only glass where 1 drop is meant to be 1 FC. The test yesterday evening was 24 and the one this morning was 22 (after sun was out about an hour) with the 10 ml from the same larger amount mixed together 50/50 (pool and rain). Then I doubled it to 20 ml where it was slightly different, and the result was 41 drops = 20 - 21 FC. This was to get an idea of the overnight chlorine loss, to see if it was close before doing the big one.
Last edited:
It's been a long day for me and my maths is currently broken. In the end, it doesn't even matter what each drop is for the OCLT. If the PM matches the AM dead on, you pass.
With what you're doing (and I understand why) if the math works, you might as well save yourself the trouble of mixing it all and just use a 5ml sample where each drop is 1.
But. For the OCLT, I'd want to use 10ml / .5 FC. There's more chance of inaccuracy with 1 FC drops. With normal pool operation, or for the bulk of the SLAM, it'll extend your hard to get supply using 1 FC drops. But failing the OCLTs when you should have passed is It's own headache.
Newdude, I think 20 ml is .5 FC, 10 ml is 1 FC (50 pool water, and 50 tab water). Unless you mean only the pool water? I dont understand but the Chlorine is always a few points lower in the morning and I have been on slam for over a week. I have checked and cleaned all the areas, and the pool is super clear.
- Jun 1, 2018
- 14,109
- Pool Size
- 26000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Watch this 
As for the pipe I’d cap it/plug it. Is it threaded? Hard to tell
As for the pipe I’d cap it/plug it. Is it threaded? Hard to tell
- Mar 5, 2020
- 3,211
- Pool Size
- 66000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V35
To get 0.5ppm/drop, just use 10ml of pure pool water. No point in watering down a pool sample and then take the double quantity to get to where you started. Just adds unnecessary error having to measure 3 quantities (pool water volume, rain water volume and then sample volume from the mixture), rather than just measuring 10ml in the first place.
The dilution only makes sense when that's the most precise way to get a sample for 1ppm per drop. If you have a 10ml syringe, then I would just use that to measure a 5ml sample of pool water for a 1ppm/drop test.
The dilution only makes sense when that's the most precise way to get a sample for 1ppm per drop. If you have a 10ml syringe, then I would just use that to measure a 5ml sample of pool water for a 1ppm/drop test.
Watch this
As for the pipe I’d cap it/plug it. Is it threaded? Hard to tell
There is no thread, but I can still put a cap on it I think. Will look in the morning. Thank you
I believe someone higher up in the thread said to mix together an equal, larger part of pool and tap water and then use 10 ml and each drop would then be 1 FC, but you think it would be better just to use 10 ml pool water alone although I need double the amount of drops? You are saying if I have a syringe, I can in that case do 5 ml pool water (as more exact measurement) for 1 FC each drop instead of .5?
Last edited:
- Mar 5, 2020
- 3,211
- Pool Size
- 66000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V35
The dilution and then a 10ml sample of the diluted water is a good option when you don't have a way to reliably measure a 5ml sample, because then you can just use the normal 10ml mark on your test vial.
If you have a way of measuring directly 5ml, like with a syringe, then I would do that as it is quicker, and more accurate than the dilution which requires multiple volume measurements.
In the end, you need 5ml of pool water. Whether that is just 5ml of pool, or 5ml of pool water plus 5ml of rain or distilled water, doesn't affect the test in principle.
It's about how can you minimise the measuring uncertainty in getting the 5ml right. When just using the graduations on the test vial, an error in fill height of let's say 0.5mm will have a larger impact on a 5ml sample compared to a 10ml sample. When using a syringe, then you can get 5ml fairly accurate. If that's not available then I would use the dilution method. Then you can make a fairly accurate 50:50 mixture by mixing larger quantities and then take a normal 10ml sample.
When at high FC during a SLAM, then you can save some reagent by using above methods to get a 1ppm/drop resolution. It's better to have a little bit less test resolution than run out of reagent mid-SLAM.
But as Newdude said, the final OCLT should be done on a standard 10ml sample with 0.5ppm/drop resolution.
If you have a way of measuring directly 5ml, like with a syringe, then I would do that as it is quicker, and more accurate than the dilution which requires multiple volume measurements.
In the end, you need 5ml of pool water. Whether that is just 5ml of pool, or 5ml of pool water plus 5ml of rain or distilled water, doesn't affect the test in principle.
It's about how can you minimise the measuring uncertainty in getting the 5ml right. When just using the graduations on the test vial, an error in fill height of let's say 0.5mm will have a larger impact on a 5ml sample compared to a 10ml sample. When using a syringe, then you can get 5ml fairly accurate. If that's not available then I would use the dilution method. Then you can make a fairly accurate 50:50 mixture by mixing larger quantities and then take a normal 10ml sample.
When at high FC during a SLAM, then you can save some reagent by using above methods to get a 1ppm/drop resolution. It's better to have a little bit less test resolution than run out of reagent mid-SLAM.
But as Newdude said, the final OCLT should be done on a standard 10ml sample with 0.5ppm/drop resolution.
I am going to do another ONCL test tonight. So let me double check this. I am going to be doing the test after the sun goes down with 10 ml of pool water, and each drop would be a half .5 of an FC? Then I will check it again tomorrow morning before the sun goes up the same way? I am going to use a syringe. FYI, I had 15 FC this morning (as I did not throw anything in in two days), so I put back in 3 gallons of bleach this morning to get back to the 24, I assume it will have between 21-24 this evening when we check?
10 ml pool water, each drop is .5 FC.
Both tests are in the dark, and well mixed.
Brush it well to stir it up with the solar pump likely out of commission.
Both tests are in the dark, and well mixed.
Brush it well to stir it up with the solar pump likely out of commission.
- Mar 5, 2020
- 3,211
- Pool Size
- 66000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V35
Sounds like a plan.
For 10ml the syringe is not really required, but doesn't hurt.
I actually always use a syringe for 10ml samples, I find it easier and faster to just pull up a syringe to 10ml than eyeballing the fill line on the test vial. Some use Taylor's nifty sample sizer for that.
25ml samples (for TA), I fill directly into the vial to the fill line, that gets far too fiddly with a syringe, and I don't do this test that often.
So guys, I did the overnight chlorine loss test night before last. In the night it was 38 (we didnt mix the water then as the pump would have been on only an hour or so before) and then in the morning it was 34 drops (we mixed it with the pool stick for 10 min). So basically in the night it was 19 and then early in the morning 17 FC...I have had guests for so its not been easy but every day we have still been putting in 2 - 3 gallons of liquid bleach (5%) to try to keep the level up. I am also in touch with the plumber to get a cover on that drain.
The goal is 1ppm or less. 2ppm is very close. If you are starting at SLAM level it’s really close.
It was not on the slam level due to having guests. It was 19 and in the morning it was 17. My slam level currently is 24.