Need some basic advice -TA, pH, CH, FC all things chemical

[mgtfp]

all but the oak are my neighbors

Tell me about the neighbour's tree. Our neighbour has a gum tree. Beautiful tree, but gums lose leaves like crazy in summer. And they shed strings of bark. No automated system can keep up with these, only way is the good old net.

But I haven't found that leaves and bark create much of extra chlorine demand. At least not at the FC I am maintaining (10% of CYA seem to work well for me).

What's important to understand is that chlorine kills organics already at very low levels, but the kill rate is proportional to the HOCl concentration. If the kill rate is higher then algae's reproduction rate, then a little bit of chlorine will kill whatever got in fast, and you're done. At lower levels, chlorine will also kill some algae, but by the longer time it takes to kill what initially got in, some algae will have reproduced, meaning that you will need more algae to eventually kill everything, and you might in total notice a higher chlorine demand.

So, and that is just me thinking out loud, it could make sense that a pool that has a high intake of algae spores needs a higher FC level compared to a pool that is easy to keep clean.

I guess, with running the pump on 24/7 with the SWG on a low setting, you will get to a situation where you will build up some chlorine overnight, whereas during the day you will be underproducing. You'd call it dialled in when FC at sunset and after all the bather load is still above your minimum level. In the morning, you'll reach the high point.

Whereas with running the pump just during the day (let's call it 12/7), you'll be more or less replacing chlorine as it gets used, resulting in a more even FC throughout a 24h period.

Assuming that both approaches would be dialled in so that the overall min is the same, the 24/7 method will probably produce more of an overshoot during the night, whereas the 12/7 method will maintain a more even FC closer to your min the whole time.

It might not just be the overall min, but also the average FC throughout the whole day that needs to be considered when comparing different chlorination schedules. And maybe the 24/7 wins in terms of lowest possible min levels.

I'm not saying that's what it is, just thinking out loud. Happy for feedback.

In summary, running 24/7 in a way that on hot, high UV days with high bather load you reach your overall min FC, and not being OCD about adjusting the SWG for every single cloudy day, is probably the way that's allowing the lowest overall min FC. But practically, you'll be higher most of the time, often by a lot.

 

[Oly]

To return to the topic at hand, what soil concentration of Cl will kill a live oak?

It will be less expensive to water it only from your salt water pool, unless its a Live Oak or Coastal Live Oak. They are more tolerant so it may take a bit longer.

 

[Orion7319]

So, and that is just me thinking out loud, it could make sense that a pool that has a high intake of algae spores needs a higher FC level compared to a pool that is easy to keep clean.

Algae grows on everything in my yard. Furniture, fence, side of the house. I have a lot of shade and it seems to thrive. I do get it with bleach and the pressure washer when it gets bad.

 

[SoDel]

Tell me about the neighbour's tree. Our neighbour has a gum tree. Beautiful tree, but gums lose leaves like crazy in summer. And they shed strings of bark. No automated system can keep up with these, only way is the good old net.

But I haven't found that leaves and bark create much of extra chlorine demand. At least not at the FC I am maintaining (10% of CYA seem to work well for me).

What's important to understand is that chlorine kills organics already at very low levels, but the kill rate is proportional to the HOCl concentration. If the kill rate is higher then algae's reproduction rate, then a little bit of chlorine will kill whatever got in fast, and you're done. At lower levels, chlorine will also kill some algae, but by the longer time it takes to kill what initially got in, some algae will have reproduced, meaning that you will need more algae to eventually kill everything, and you might in total notice a higher chlorine demand.

So, and that is just me thinking out loud, it could make sense that a pool that has a high intake of algae spores needs a higher FC level compared to a pool that is easy to keep clean.

I guess, with running the pump on 24/7 with the SWG on a low setting, you will get to a situation where you will build up some chlorine overnight, whereas during the day you will be underproducing. You'd call it dialled in when FC at sunset and after all the bather load is still above your minimum level. In the morning, you'll reach the high point.

Whereas with running the pump just during the day (let's call it 12/7), you'll be more or less replacing chlorine as it gets used, resulting in a more even FC throughout a 24h period.

Assuming that both approaches would be dialled in so that the overall min is the same, the 24/7 method will probably produce more of an overshoot during the night, whereas the 12/7 method will maintain a more even FC closer to your min the whole time.

It might not just be the overall min, but also the average FC throughout the whole day that needs to be considered when comparing different chlorination schedules. And maybe the 24/7 wins in terms of lowest possible min levels.

I'm not saying that's what it is, just thinking out loud. Happy for feedback.

In summary, running 24/7 in a way that on hot, high UV days with high bather load you reach your overall min FC, and not being OCD about adjusting the SWG for every single cloudy day, is probably the way that's allowing the lowest overall min FC. But practically, you'll be higher most of the time, often by a lot.

These are really good thoughts. On sunny days when there’s not much else to do (it happens by luck sometimes, and these are days to remember! (10,000 maniacs reference)) would be worthwhile to test the FC over the course of the day and see what’s what. Exactly what you are saying has to be true.

 

[SoDel]

Algae grows on everything in my yard. Furniture, fence, side of the house. I have a lot of shade and it seems to thrive. I do get it with bleach and the pressure washer when it gets bad.

Yikes! My bet would be plenty of spores and plenty of environmental conditions that make algae thrive. On the bright side, the rest of your landscaping must be doing amazing. Green thumb and all.

 

[SoDel]

It will be less expensive to water it only from your salt water pool, unless its a Live Oak or Coastal Live Oak. They are more tolerant so it may take a bit longer.

Dicamba (or 2-4d or triclopyr or, if you’re a Marine and it absolutely, positively needs to get dead, Tordon) FTW!

 

[SoDel]

Tell me about the neighbour's tree. Our neighbour has a gum tree. Beautiful tree, but gums lose leaves like crazy in summer. And they shed strings of bark. No automated system can keep up with these, only way is the good old net.

But I haven't found that leaves and bark create much of extra chlorine demand. At least not at the FC I am maintaining (10% of CYA seem to work well for me).

What's important to understand is that chlorine kills organics already at very low levels, but the kill rate is proportional to the HOCl concentration. If the kill rate is higher then algae's reproduction rate, then a little bit of chlorine will kill whatever got in fast, and you're done. At lower levels, chlorine will also kill some algae, but by the longer time it takes to kill what initially got in, some algae will have reproduced, meaning that you will need more algae to eventually kill everything, and you might in total notice a higher chlorine demand.

So, and that is just me thinking out loud, it could make sense that a pool that has a high intake of algae spores needs a higher FC level compared to a pool that is easy to keep clean.

I guess, with running the pump on 24/7 with the SWG on a low setting, you will get to a situation where you will build up some chlorine overnight, whereas during the day you will be underproducing. You'd call it dialled in when FC at sunset and after all the bather load is still above your minimum level. In the morning, you'll reach the high point.

Whereas with running the pump just during the day (let's call it 12/7), you'll be more or less replacing chlorine as it gets used, resulting in a more even FC throughout a 24h period.

Assuming that both approaches would be dialled in so that the overall min is the same, the 24/7 method will probably produce more of an overshoot during the night, whereas the 12/7 method will maintain a more even FC closer to your min the whole time.

It might not just be the overall min, but also the average FC throughout the whole day that needs to be considered when comparing different chlorination schedules. And maybe the 24/7 wins in terms of lowest possible min levels.

I'm not saying that's what it is, just thinking out loud. Happy for feedback.

In summary, running 24/7 in a way that on hot, high UV days with high bather load you reach your overall min FC, and not being OCD about adjusting the SWG for every single cloudy day, is probably the way that's allowing the lowest overall min FC. But practically, you'll be higher most of the time, often by a lot.

I did some pump flow testing this am and changed to 24/7. Pump speed 65% for 12 hrs (what it was) with 40% for 12 hrs added. As a starting point, I just halved the SWG % on time to adjust for the 2x pump run time. Another member here helped me with setting up the controller so I don’t get the jet engine when priming effect when the speed reduces. It will prime every morning (same as before) just in case.

I’ll continue testing FC every morning and adding some mid-day and end of day testing from time-to-time to see what’s going on. If anything interesting emerges, I’ll post it.

 

[SoDel]

Morning coffee pondering again. Have SWG, still lowering TA from the winter slumber as temps rise, yadda, yadda, ISO slower pH rise, yadda. I’ve read that with very low TA, the risk is pH crash. What would be the causes of this crash? Is it just bather load?

 

[Texas Splash]

If your TA goes too low, let's say below 40 for example, the pH can become erratic. The pH can then fall if pool products and/or local water conditions are acidic. So remember the golden rule - if your pH is happy and remains fairly stable, there is probably no need to force the TA down.

 

[SoDel]

Oh, I’ve tried and tried to make my pH happy but it remains inconsolable. Right now I’ve got TA down to 80 with 30 CYA, 450 CH. pH rises about 0.2 to 0.3 per day and needs a pint or so of acid every other day. Hoping to reduce my steady state CO2 and let pH hover between 7.8-8.0 with longer intervals between acid additions. I’ve resisted forcing TA down, just keep adding acid as it needs it and letting it naturally fall. You’ve educated me on when I need to add a little bicarb as this likely continues.

No huge aeration sources, but spa does trickle all day long. That setup has been working so well in terms of keeping the spa as clear as the pool that I hesitate to mess with it. I foresee if switching to flushing the spa x times per day and minimizing aeration just right and, and, and ohnoos, spa is green lol. Oh Crud, I may mess with it after all. Wish me luck lol.

 

[SoDel]

If your TA goes too low, let's say below 40 for example, the pH can become erratic. The pH can then fall if pool products and/or local water conditions are acidic. So remember the golden rule - if your pH is happy and remains fairly stable, there is probably no need to force the TA down.

It seems to be working! TA now down to around 70 and went 4 days for rise from 7.4 to 7.8. Just held at 7.8 for two days. Progress! (sorry to be exited about this but when practice matches the theory, it’s exciting — I know, get a hobby lol).