How much chlorine do I need to kill algae, given these parameters?

[frogabog]

This is EXACTLY what I discovered just now, when I tested, 24 hours after seeing a 2.5ppm loss in the first 24 hour period. What I saw today was an 8ppm loss over the 2nd 24 hour period! In fact, I was just getting back on here to post a question as to what might cause this, aside from testing error (more on that below), when I saw your post. The good news is that the remant patches on the plaster that have been brushed daily since starting this endeavor 3 days ago(?) are almost all gone. This fact, combined with the nearly triple FC loss I just recorded, along with your post and what someone else previously said, leads me to believe that such a big FC loss today could be partly contributed to the recent sustained higher FC level indeed being effective at killing off the algae in my pool, thus the consumption of much more FC than the first day. Granted, this assumption is based purely on what I can see, and this theory may not hold water (pun intended). That said, even if this theory is correct, this doesn't mean that I am inclined not to SLAM.


Au contraire, when I do SLAM, I will maintain that SLAM FC level as best I can, but will likely only be able to add LC twice a day.


All the more reason to ensure CYA is properly tested.

Speaking of which, I was actually wondering earlier if it was possble that my CYA test results were wrong, which might explain why I am seeing such good (in my eyes) results with the algae thus far. I doubt I erred, though, because I did the regular test first, which prompted me to subsequently do the diluted test, so I had to have been wrong twice in quick succession. To clarify, the normal test resulted in the cloudy water not even getting up to the 100 mark, and it was shy by a considerable amount. However, when I did the diluted test, it hit 50 on the nose, which indicates my level is supposedly 100. If I was wrong (first time I ever hoped I was) in my test, and my CYA is really more like 30, then I would be slamming at the levels I have been trying to keep thus far. But, that's a far reach, especially since I've been running the trichlor pucks for so darned long.


Nice thougt here, but wouldn't downspout water be too dirty to put in a pool? I have a tile roof and when I clean my gutters I see all kind of sand from the erosion of the tile in the gutters, not to mention leaves and all that. Or, is that OK, as long as that stuff isn't swimming in the water column?

While we don't have rain often, when we get it, it's BIG! I live in the foothiils right above a big lake, and the storm clouds come across the lake and park at the hills and just preciptate water out of the lake and dump them on my house. I can drive 5 miles down the hill or even just across the lake, and it will be sunny, but when I look toward my house it's black and you can't even see the hillside. So, I'm trying to live with the high CYA for the next few months. Of course, I may lose patience along the way. ;-)

I think you'll find varying amounts of chlorine lost while you're dealing with the algae. After you're done with that and maintaining at the high target for your CYA, then you'll see more consistent daily losses that align with the ~50% that pools without issues see. Normally we dose the pool at night to target, and expect to lose not quite enough to be at minimum by the next night, rinse and repeat daily. If you have extra swimmers or other conditions, then you may need to put some extra chlorine in. Right now, your chlorine loss probably is higher since you're battling the algae, although with CYA at 100 50% might very well be in the 8ppm range. It sounds like you're a solid 100, I did remember you said you did the diluted test so I didn't question it.

Insofar as the rain water, the turbidity from the roof dirt should not be much if you don't stir it up when you remove the water. Most solids will settle to the bottom, and you'll also want to put a little chlorine in the water so as to not get algae in the rain barrels. You could also invest in a small handheld pool vacuum if it really bothers you. I had one of those once and it worked pretty well.

Have you thought of going down to that lake and collecting some water? It may take some time to do enough to get 50% of your water replaced, and the water itself might have a little lake algae but it could be a way to get water for free. I once saw someone filling a waterbed bladder in the back of a pickup truck from the Willamette river with a pump. I think it was for watering plants since we were having a drought at the time.

Of course, I see the point you're making about the SLAM level and black algae. The article does say to keep your FC within the range between target and SLAM. I think folks around here are just more inclined to use the SLAM level if it's part of the options rather than a lower level because it's a lot easier on YOU if your water gets cleared up faster than slower.

Since you have to leave now... there's a chance you'll backslide unless someone can put chlorine in the water for you. I'd suggest hitting it hard while you can, which of course means lots of chlorine!

Oh, and if you do end up needing to SLAM, note that testing and adding 2x a day will make it a very slow, if not potentially ineffective process. 3x a day is the bare minimum. People who do 2x a day seem to spend considerable time posting wondering why it's not working yet... people who can do it 3+ times a day see good results.

 

[an1vrsy]

Does that mean there is no MrsLeadfoot to add chlorine while you’re out of town? Or a trusted neighbor or close friend? You’d set up jugs of chlorine ahead of time and get them to pour it in.

 

[DuaeGuttae]

About collecting rain water: I use tanks that are screened on top. That catches large debris. I tried putting a sock on the end of the garden hose when I first experimented with this, but there wasn’t anything of significance for it to catch. There is some sediment that builds at the bottom of the tank, but the hose doesn’t draw from quite that far down.

There are downspout diverters that allow a person to choose to collect rainwater or to allow it to continue to the ground. Such diverters let the first few minutes of rain wash the roof and then the rest be directed to tanks. We do not use those as we don’t even actually have gutters. When I moved to this part of the country and was told by a realtor that gutters are considered an upgrade on a house, I was quite shocked. I had considered them to be something pretty standard like windows. He found that surprising.

About being out of town: you mentioned a son. Is he old enough and responsible enough to pour designated jugs of sodium hypochlorite into your pool each day?

 

[MrLeadFoot]

I think you'll find varying amounts of chlorine lost while you're dealing with the algae. After you're done with that and maintaining at the high target for your CYA, then you'll see more consistent daily losses that align with the ~50% that pools without issues see. Normally we dose the pool at night to target, and expect to lose not quite enough to be at minimum by the next night, rinse and repeat daily. If you have extra swimmers or other conditions, then you may need to put some extra chlorine in. Right now, your chlorine loss probably is higher since you're battling the algae, although with CYA at 100 50% might very well be in the 8ppm range. It sounds like you're a solid 100, I did remember you said you did the diluted test so I didn't question it.

Yes CYA is supposedly 100.

Insofar as the rain water, the turbidity from the roof dirt should not be much if you don't stir it up when you remove the water. Most solids will settle to the bottom, and you'll also want to put a little chlorine in the water so as to not get algae in the rain barrels. You could also invest in a small handheld pool vacuum if it really bothers you. I had one of those once and it worked pretty well.

As I think further about it, I really only need to exchange water once, so I may not need to store any water. The rains in one season will likely be all I need.

Have you thought of going down to that lake and collecting some water? It may take some time to do enough to get 50% of your water replaced, and the water itself might have a little lake algae but it could be a way to get water for free. I once saw someone filling a waterbed bladder in the back of a pickup truck from the Willamette river with a pump. I think it was for watering plants since we were having a drought at the time.

Good idea! I have a bass boat and go out on a weekly basis. I have a 40 gallon livewell, which I never use because I practice catch-and-release. While it's not much, I can execise patience, and if I am constantly diluting my water, CYA will drop over time. Instead of wasting time checking CYA all the time, I can simply maintain the FC level for 100 CYA, and then check it again next summer. The ONLY, yet BIG, concern I have with this is potentially introducing other, WORSE forms of algae, like the dreaded mustard algae. I'll have to think about this a bit.

Of course, I see the point you're making about the SLAM level and black algae. The article does say to keep your FC within the range between target and SLAM. I think folks around here are just more inclined to use the SLAM level if it's part of the options rather than a lower level because it's a lot easier on YOU if your water gets cleared up faster than slower.

That's one perspective, but I was kind of wondering if SLAMming is overkill for black algae, meaning that once you have a level that kills it, more is not necessaarily better, which might be exaclty why there is a separate article on black algae, as it might an exception. I don't know for sure, just guessing.

Since you have to leave now... there's a chance you'll backslide unless someone can put chlorine in the water for you. I'd suggest hitting it hard while you can, which of course means lots of chlorine!

I definitely don't want a backslide now. It's not like the black algae is everywhere, so I only had to brush a few spots. It's brushing all the grout lines that's a real PITA. You have to look so hard at them, you end up cross-eyed, and I was already cross-eyed having a cram course in pool chemistry.

Oh, and if you do end up needing to SLAM, note that testing and adding 2x a day will make it a very slow, if not potentially ineffective process. 3x a day is the bare minimum. People who do 2x a day seem to spend considerable time posting wondering why it's not working yet... people who can do it 3+ times a day see good results.

So maybe a SLAM should be done when I have consecutive days I can be available.

 

[frogabog]

When I moved to this part of the country and was told by a realtor that gutters are considered an upgrade on a house, I was quite shocked. I had considered them to be something pretty standard like windows. He found that surprising.

Not intended to hijack this thread but... WHA????

So how do you collect rain? When it rains, does it just fall off the roof everywhere along the whole house? Doesn't that make swampy rain lines in the ground surrounding your house? I assume you don't have basements, but if you did... do they leak?

I'm shocked about the no gutters thing too. Do you see so little rain that it evaporates before it falls off the roof? hehe

 

[MrLeadFoot]

Does that mean there is no MrsLeadfoot to add chlorine while you’re out of town? Or a trusted neighbor or close friend? You’d set up jugs of chlorine ahead of time and get them to pour it in.

Mrs. LeadFoot will be in traffic court. Just kidding, she's going with me.

Seriously, though, it's starting to sound like this method of caring for a pool is only practical when you can meet the following criteria:

1) You are retired or are otherwise available to be at your pool's beck and call on a daily basis.
2) You don't travel.
3) You have a heckuva lot of friends who don't mind coming over and risking bleaching their clothes to dose your pool if you're gone for more than 24 hours.
4) You have SWCG.
5) You have access to cheap replacement water, so you can supplement with Trichlor pucks when you're away, and when your CYA levels get too high, you simply exchange some water.

Surely, there's got to be another way for people like me who don't meet all these requirements. I am open to suggestions on how to maintain a decent level of chlorine without being slave to the pool every single day.

 

[MrLeadFoot]

About being out of town: you mentioned a son. Is he old enough and responsible enough to pour designated jugs of sodium hypochlorite into your pool each day?

There it is again, the daunting prospect of being owned by your pool. Holy Smoke, is there really no other product out there except a SWCG that can dose your pool while you're gone? Yes, my son is capable and will be here, but really, is there nothing like a puck without stabilizer in it out there? What if you simply forget, get sick, or are simply too tired just one day? Your whole water chemistry goes out the window, opening you up for a host of potential problems? Surely someone has devised a scheme by now, out of the thousands of people subscribing to this method of poolkeeping. Let's hear from you folks! ?

 

[mknauss]

Chlorine must be bound to something, as it is a gas in its natural state.
Solid chlorine products are either bound to CYA or Calcium.
Liquid chlorine is bound to water.

A SWCG makes your chlorine. You can install a liquid chlorine dispensing system. Search Stenner pump systems.

We leave for weeks at a time. Our SWCG adds chlorine for us.

 

[DuaeGuttae]

There are pumps that can be set up to dose chlorine or acid. Search Stenner pumps. Now you know why SWCGs are pretty popular around here.

I remember a post by a member named Dirk who struggled with the same issue even after he had a SWCG if I recall correctly. He used a Stenner pump to dose acid so that he could quit, as I think he wrote, being held hostage by his pool.

Stick out the tough phase of managing your immediate problem, and then you can start delving into how to handle the longer term. It is overwhelming at first, but you can figure out what you’ll need to do to make it work for your circumstances.

 

[MrLeadFoot]

Chlorine must be bound to something, as it is a gas in its natural state.
Solid chlorine products are either bound to CYA or Calcium.

Does this mean what I think it means? Get pucks that run your CYA up, like what happened to me, or get pucks that run your calcium up, as in what the CH test checks for? We already know that high CYA makes you eventually have to get into chemotherapy with large amounts of chlorine, but what happens with too much calcium - is that how you get scale, or something? If so, it sounds like the lesser of two evils to me, both of which eventually require a water exchange of some sort.

How do pool services do it, then? They typically visit only once a week. Surely, they don't rely on pucks to the eventual detriment of their customers' pools, or do they?

A SWCG makes your chlorine. You can install a liquid chlorine dispensing system. Search Stenner pump systems.

Doesn't sound like I can do anything by Friday.

We leave for weeks at a time. Our SWCG adds chlorine for us.

Show off!

 

[DuaeGuttae]

Not intended to hijack this thread but... WHA????

So how do you collect rain? When it rains, does it just fall off the roof everywhere along the whole house? Doesn't that make swampy rain lines in the ground surrounding your house? I assume you don't have basements, but if you did... do they leak?

I'm shocked about the no gutters thing too. Do you see so little rain that it evaporates before it falls off the roof? hehe

Can you see the stream in the first picture? If the rain is too light, it undershoots, too heavy, it goes over, but we can easily collect 500 gallons in that tank in one crazy storm. When that tank is full, we use hoses to transfer to others that don’t collect water as readily.

We go months with no significant rain, but when it comes, it comes. The rain tank in the second picture has a spigot at the bottom. You can’t even see it because of the inches of water. Sometimes it really is so light that it just evaporated as you suggested.

There are no (or at least very few) basements here. What’s even more amazing is that even after a “frog strangler” rain, it really isn’t swampy. We have one spot where there might be something like mud on occasion, but I describe our house as being built on a limestone cliff. The water rushes off or sinks pretty quickly into the aquifer.

Our water is actually pretty cheap per gallon, but there are restrictions on use. They’re less severe this year than last (I can now top up the pool two times per week instead of just one), but I do love storing my good rain water and using it just when I want. (I also like using it to keep CH and TA down, but that’s again because of that limestone cliff where I live).

 

[MrLeadFoot]

There are pumps that can be set up to dose chlorine or acid. Search Stenner pumps. Now you know why SWCGs are pretty popular around here.

I remember a post by a member named Dirk who struggled with the same issue even after he had a SWCG if I recall correctly. He used a Stenner pump to dose acid so that he could quit, as I think he wrote, being held hostage by his pool.

Stick out the tough phase of managing your immediate problem, and then you can start delving into how to handle the longer term. It is overwhelming at first, but you can figure out what you’ll need to do to make it work for your circumstances.

But, my leaving will likely prevent me from seeing this darned immediate problem through! I've invented some pretty clever things in my time, including making software out of just ideas. Surely, someone has come up with some creative way aside from expensive equipment or buying people. What about throwing in 10 or 20 gallons of bleach or something? Ten gallons should get me to 40ppm or so, and 20 will get me to 65ppm. Is that bad to do? Will it eat my plaster and pool cover?

 

[mguzzy]

There are solid products you can put in your floater that will not increase your CYA.. Cal Hypo for example but they have their own side effects or just use your pucks and deal with the CYA when you get back.. it not like you haven't been in this state of high CYA already..
How to Chlorinate Your Pool - Trouble Free Pool

 

[DuaeGuttae]

But, my leaving will likely prevent me from seeing this darned immediate problem through! I've invented some pretty clever things in my time, including making software out of just ideas. Surely, someone has come up with some creative way aside from expensive equipment or buying people. What about throwing in 10 or 20 gallons of bleach or something? Ten gallons should get me to 40ppm or so, and 20 will get me to 65ppm. Is that bad to do? Will it eat my plaster and pool cover?

This gets a little over my head, but I’ll do my best. If your CYA level is 100, your slam level is 40. That’s perfectly safe. There’s an even higher mustard algae slam level that can be done for 24 hours, but I don’t know that off the top of my head.

What kind of cover do you have? If it’s pretty solid, it will protect your higher chlorine levels a bit more, and you wouldn’t see so much UV degradation. Even our mesh cover slows chlorine loss when it’s on. I think I’ve read where there can be a buildup of combined chloramines under a solid cover, and it needs to be opened to allow the UV to break them down and allow them to outgas. I don’t know if they could harm your cover in five days.

I wouldn’t add any pucks because you know your CYA is high already, and you really don’t want to drain. Even if your chlorine can’t last above your minimum all five days, you’ve shown determination to do the SLAM process if necessary. Take what precautions you can and deal with it when you get back.

Home Depot around here sells 10% chlorinating liquid in a 3 pack for 9.98. The price goes down to 8.98 at the register if you buy four packs. Just make sure to check the Julian dates.

 

[DuaeGuttae]

I just looked up the mustard algae shock level, and it’s apparently 60% of your CYA as opposed to 40% for normal shock level. The actual chart gave numbers like 57.3 ppm and 39.1 ppm for a CYA of 100, so I’m a bit mystified as to the actual math there. I’m sure there’s a chem geek explanation somewhere.

Maybe @JoyfulNoise can suggest a helpful chlorine level given your time constraints and your cover.

 

[frogabog]

Ugh! It took me so long to find this... but I did finally find it!

You may be interested in this DIY liquid chlorine pump if you're looking to save some cashola.

Cheap liquid chlorine injection system (stenner alternative)

Parts needed: 1. A chemical pump 2. A Stenner injection valve ( with or without checkvalve) 3. A chemical storage tank 4. Timer to run it My Parts: 1. $83.20 Ebay does coupons for 15% or 20% off events once or twice a month...

www.troublefreepool.com

 

[MrLeadFoot]

Ugh! It took me so long to find this... but I did finally find it!

You may be interested in this DIY liquid chlorine pump if you're looking to save some cashola.

Cheap liquid chlorine injection system (stenner alternative)

Parts needed: 1. A chemical pump 2. A Stenner injection valve ( with or without checkvalve) 3. A chemical storage tank 4. Timer to run it My Parts: 1. $83.20 Ebay does coupons for 15% or 20% off events once or twice a month...

www.troublefreepool.com

Thank you.

 

[mguzzy]

Ugh! It took me so long to find this... but I did finally find it!

You may be interested in this DIY liquid chlorine pump if you're looking to save some cashola.

Cheap liquid chlorine injection system (stenner alternative)

Parts needed: 1. A chemical pump 2. A Stenner injection valve ( with or without checkvalve) 3. A chemical storage tank 4. Timer to run it My Parts: 1. $83.20 Ebay does coupons for 15% or 20% off events once or twice a month...

www.troublefreepool.com

I don't think MrLead' will have time to implement that before he leaves... how about this from here:

OK, ya'll.. so we are back to trying to do this with just what is on hand.. I have to say I have lots of junk in my garage to try lots of different things. As they say everything at TFP is based on science, so lets head to the chalk board first.
I'm thinking setting up a siphon might be the better than trying to let it drip out a hole in the bottom of the jug. The liquid draining from a hole in the jug will slow down as the weight of the liquid lessens, and Van der Waals forces or surface tension may even cause it to stop if the hole is small enough. And if the lid is left on, the lower air pressure of the air space above the liquid will create enough suction to stop the flow out the hole. Whereas a siphon will drain at a constant velocity (flow) based on the relative height of the surface of the liquid in the jug compared to the height of the opening of the tube. Per Bernoulli's equation we get:

where v is velocity, g is gravity, and h is the difference in height between the top of the liquid and opening of the tube. So much for theory.. let's make one. As I proof of concept I used an old chlorine jug with water and a clear tube from my box of random tubes from the garage.

View attachment 113133
I created a makeshift flow control clamp with some silverware from the kitchen and a binder clip from the office drawer. The binder clip alone did not provide enough surface area to clamp the tube. I was going to use Popsicle sticks but I wasn't finished with the one I was still eating.
View attachment 113134
I got a steady constant drip and I think with some fussing I can regulate it. By dripping into a measuring cup and dividing the volume filled by the time to fill it, I should get a pretty reliable rate of dispensing. And using a longer tube to put the jug higher up (bigger "h"), should make the effect of the flow difference caused by the height of the bottle negligible.

Will that do it for ya?

 

[MrLeadFoot]

OK, here's what I've learned in the short time I've been on this forum, and am posting this to possibly help others who might find themselves with high CYA (read the rest of the pool owners in the world not on this forum) and a black algae problem:

1) Everyone tries to help! Doesn't matter what they say, everyone's heart is in the right place. No flame throwers in the mix, which is such a welcoming experience. What a community!

2) Like the PoolSchool article says, black alage, without a doubt, does not require a SLAM. In fact, it may not even require an FC level between your high target and SLAM levels, as the article suggests. I cannot say this for sure, but it's been so easy to deal with, once I got up into my proper target range which is literally 10x what I'd been running at for years, due to NOT HAVING THE RIGHT TEST KIT. It is possible that the sudden jump in levels was enough to shock the algae to death being as it might simply have been a case of it living comfortably at 1.5ppm, then suddenly not being able to withstand 12ppm or so, although I did get up to 14.5 for a short period ( which is only 1.5 above my high target value). I actually wonder if just being in the proper target range would have been enough. Regardless, kudos and a big thank you to whoever decided that an article dedicated specifically to resolving black algae was important to have as a distinction from all other conditions.

3) I said what I said about not needing to SLAM in #2 above because my black algae is almost all gone. I say "almost" because, due to my inexperience, I did not initially pay enough attention to the little spots between some grout lines, and a few other spots described in #4 below, when brushing, so those were a day behind in being eradicated. You should absolutely look everything over from the start to ensure you brush it all when you start, so you eradicate it all at once.

4) You can get bruises from kicking yourself in the behind for being a nitwit. In this case, I didn't initially think about removing the collar nuts on my return inlets and my suction side port so I could clean behind them. I woke up this morning to a nearly black algae-free pool, only to notice that the algae behind the collar nuts was not affected by the chlorine at all obviously due to me not brushing the protective layer off. So, I removed the collar nuts and brushed it all off, and kicked my own butt as I watched it all fall to the bottom of the pool! Gosh, my butt hurts now. Lesson be learned. Don't be like me! Good news is that I know it will be dead and gone when I get back from work this afternoon.

To those of you have been following my epic saga (at least that's what it's been to me), I would say that the back algae is 98% gone, the spots I missed brushing entirely as described in #4 above notwithstanding. There are miniscule remnants that are deep into some pores in the plaster, but to brush that out will likely leave deep gouges in the plaster, or wear it away altogether. I am confident that the proper FC level will kill it soon enough though, and if what I've seen thus far is any indication, it'll be gone when I get home from work this afternoon. Another lesson to be learned is to get it while it's hot so the black algae doesn't have the opportunity to establish deep roots.

Oh, I almost forgot. My overnight FC level loss was only 1.5, and I really thought I was almost done, until I found the hidden algae behind the nut collars. Nevertheless, I am very pleased with the results, and can't wait to be able to test overnight loss again once the last pieces I found this morning are gone.

Now, on to trying to find a way to chorinate practically, instead of playing 50 Shades of Grey by being slave to my pool!

 

[ajw22]

Do you have any light niches? Considering all the places you found algae you might want to remove any lights and check in the niche.