Nightmare black algae

[Lankyone]

Hi guys , having a bit of a nightmare with black spot algae in a salt pool that's not mine but trying to clear it up before I leave , when I got here it looked like a carpet of algae on the walls but dose of calcium hypochlorite followed by 3 days with a dive mask and a hand scrubbing brush and lots of hoovering to waste it looked pretty good . Looking at the readings now with a basic tester ( we are in New Zealand in the middle of nowhere ) I'm getting a ph reading of 8.2 which I can bring down with Mauriac acid but it creeps back up in a couple of days the total alkalinity is 120 . The cl is reding 1.0 with the palintest pool tester

That's all the readings I can do .

Then the spots have started coming back , they are prob 1 or 2 mm across and really quite stubborn a normal pool brush doesn't get them off , and there is also a white substance that seems to be tougher than the black spots it's almost like sand but does scrub off with the hand brush

So In summary , I could prob get another load of hypo but it's 3 hours drive and the shop that sells it doesn't seem to know anything I had no idea how thick the algae was when I first put the dose in , so I think its effectiveness could have been restricted !

And the pH comes up really fast I've read that salt pools do this anyway but 2 days seems very fast (I've never really come across salt pools )

There is also possibly a problem with the control box it runs fine on filtration , but if you turn the 6 pos to waste or backwash it comes up with low flow , but the waste is pumping loads of water out so I really don't think it is that

HELP PLEASE

It's a zodiac control panel, a fibreglass pool ( one piece thing ) and a serious headache !!

Any help would be amazing !!

 

[Divin Dave]

Man, Black Algae is tough, and i reckon next to impossible to get rid of without a good test kit.

Ph rising that quick isnt unheard of, if you could get the TA down to about 80, it might help slow down the Ph rise a bit. The water flowing through the salt cell also agitates the water, which makes the Ph rise too. So its somewhat common that with a SWG, you can get quickly rising Ph. - I WOULD like to say though, that if you get your water chemistry dead to rights, you should not have a quick Ph Rise. (I have a salt pool and my Ph has been rock solid steady at 7.4 for 8 months. I have not had to add 1 drop of acid since June. I know a couple others here with the same experience, so it is possible to control it.)

Back to the algae and your chlorine levels. The proper FC level is dependent upon how much stabilizer a.k.a. CYA or cyanauric acid (or however ya spell it). If your FC to CYA ratio isnt correct, you will never get rid of algae. A sad fact but true. In any case though, the FC level of 1 is wayyyyy too low to have any effectiveness on the black algae and likely will be burned off by the sun in relatively short order.

To get rid of the algae, you are going to have to raise the FC and KEEP it at shock level for days on end until its all killed off. Unfortunately, there isnt a 1 time fix for it.

As for the low flow light. What you describe makes sense. The salt cell has a flow switch in it, and if the switch doesnt sense flow, then the low flow light gets lit up. While backwashing, there is no flow through the salt cell. Its working fine.

What all I said and what Im about to say may be somewhat of a mute point since you dont have a decent test kit and probably no hopes of getting one anytime soon. Man, I wish I could offer more, but without knowing more of your water parameters, just no way to better advise you.

For what its worth, here is a link to the TFP way of getting rid of algae, and a FC to CYA chart and other helpful stuff.
http://www.troublefreepool.com/content/125-slam-shock-level-and-maintain-shockingl

http://www.troublefreepool.com/content/128-chlorine-cya-chart-slam-shock

http://www.troublefreepool.com/content/134-recommended-levels

and here is a link to a calculator so you can figure how much of what needs to be added in order to obtain your targets
http://www.troublefreepool.com/calc.html

 

[Casey]

Welcome.

Lot of issues here... Black algae needs a high, continual dose of chlorine and brushing to irradicate it.

Second issue with white sandy substance is more likely than not calcium from cal hypo.

Can't help with the box, sorry.

I'd suggest you look into Pool School at the ABC's of pool water and see if you can get the owner of said pool to order a recommended test kit like the TF100 or the K2006.

 

[Lankyone]

Hi Dave , thanks for the reply, I had read other articles on this and feared this sort of scenario , couple of things that I can't find definitive answers to ; when adding to chlorine , hypo or liquid chlor , can I run the filter ? With a normal pool I would always run it constantly and be keen on backwashes etc but I have been warned off putting extra chlorine through the salt electrolyser because of the risk of damage and this system ( don't know if this is the norm with salt systems )

When chlorine is at shock level is it still safe to swim ( or what is safe level ? ) they have two small grandchildren so are quite concerned to not affect them , they are ok with me putting stuff in but not s keen on sketchy "about 12 hours " "maybe by the morning " type of answers

They have never used cya in the pool and I've had loads of problems with not enough sunshine cya not being used up and the level snowballing so I am just looking at adding this now , in France it's just been part of the multifunction tablets I used and seems to go at the right rate apart from 3 problem pools

I did get it to almost perfect with the scrubbing and waste Hoover the next morning when things had settled, but it just starts to come back after a couple of days , I am guessing that this is the optimum point to shock the pool when it has the least amount of stuff in it , there was a load of stuff in the lights that I didn't get last time as they seemed to think that they were sealed into the one piece pool and it would leak ( I took the chance today and it didn't , PHEW ) !

Well it seems I can tick the low flow light off the problem list so I guess that's something !!

 

[Lankyone]

Thanks Casey ,

Would the calcium buildup feed the algae ? Certainly seems to work that way ! It was the first dose of calc hypo it had ( ever I think ) and I'm not convinced I used enough , apparently there are different strengths available so it might be a weaker concentrate than I'm used to working with , also with the chems they all seem to say add water ( well product to water ) but never give how much to dilute it by ! You reckon one dose could cause visible scaling like that ?

Really appreciate all these replies guys

 

[Divin Dave]

Hi Lanky,
Yes, you indeed want to keep the pump running when you add cal hypo or chlorine or for that matter any other chemical.

the higher of levels of chlorine are fine for the salt systems. No worries man. The salt system cell actually produces chlorine. Thats why it exists. When Chlorine productions happens inside the cell, the Chlorine level is for a very short period time, (a second or 2 or 3, until its mixed with the water,), much much higher than the level in of Chlorine in the pool. So, I think prolly that maybe somebody had too much wine at pool side that came up with that one.

It is safe to swim up to Shock Level. No worries. Part 2 of the questions is obvously, "what is shock level?" well as the chart i posted a link to shows, the Shock Level is depnedent upon the CYA level. But simply, yes, its safe to swim up to shock level.

I would say that if you add enough chlorine to get to Shock Level, then wait an hour with the pump running. The chlorine will be mixed well by then and safe to swim. For additons of Chlorine in smaller amounts to keep your FC just at recommended levels, then wait 15-30 minutes to swim.

We here at TFP understand the CYA problem, and thats why we can keep our pools so sparkly and Trouble Free. People here who test their own water and go by the recommendations dont have algae problems. Can ya believe it? Im serious, we dont!

Too much of CYA, and you cannot keep FC high enough to keep the algae away.
Too Little of it, and the sunshine eats up the FC in a big hurry and that is no good either.
Finding the right level of CYA and Understanding the FC to CYA relationship is the key. TFP did not discover this, but we follow the rule of it and its based on science, not sales pitch. The pool stores and chemical making people dont follow it though, because if they did, they wouldnt be able to sell gobs of snake oil to customers with eyes that have rolled into the back of their from the BS and high price tags heaped upon them. Its really is a sad situation for the average pool owner.

CYA does not burn off or degrade. The only way to lower it is through draining some of the water and replacing it with new CYA-free water. The largest culprit we see here, are the Trichlor Tablets which are pushed hard by the Pool Store. They are largely made up of CYA and some chlorine. 1 tablet in 10,000 gallons of water can raise CYA 6 ppm. It doesnt take long of using these, until the CYA is so high, that the chlorine becomes ineffective and algae blooms.

Considering the black alageae and when to shock it. That crust on the algae is almost bullett proof. The hard part on top grows back fast too, thats why its so hard to get rid of. The best time to shock is just as soon as you come out of the pool from scurbbing it and exposing its delicate part to the chlorine. That is when you hit it hard, and keep hitting it.
As the chlorine fights the algae, it will get used up quick. Would not surprise me to see the FC level deplete by 50% in less than 4 hours of taking it to shock level. To kill the algae, you have to get the FC up and Keep it there for extended periods of time, usually several days or more... however long it takes is what it takes.

hope this helps,

Hi Dave , thanks for the reply, I had read other articles on this and feared this sort of scenario , couple of things that I can't find definitive answers to ; when adding to chlorine , hypo or liquid chlor , can I run the filter ? With a normal pool I would always run it constantly and be keen on backwashes etc but I have been warned off putting extra chlorine through the salt electrolyser because of the risk of damage and this system ( don't know if this is the norm with salt systems )

When chlorine is at shock level is it still safe to swim ( or what is safe level ? ) they have two small grandchildren so are quite concerned to not affect them , they are ok with me putting stuff in but not s keen on sketchy "about 12 hours " "maybe by the morning " type of answers

They have never used cya in the pool and I've had loads of problems with not enough sunshine cya not being used up and the level snowballing so I am just looking at adding this now , in France it's just been part of the multifunction tablets I used and seems to go at the right rate apart from 3 problem pools

I did get it to almost perfect with the scrubbing and waste Hoover the next morning when things had settled, but it just starts to come back after a couple of days , I am guessing that this is the optimum point to shock the pool when it has the least amount of stuff in it , there was a load of stuff in the lights that I didn't get last time as they seemed to think that they were sealed into the one piece pool and it would leak ( I took the chance today and it didn't , PHEW ) !

Well it seems I can tick the low flow light off the problem list so I guess that's something !!

 

[Divin Dave]

Lanky,
depending on the quantity of calcium in the cal hypo, and what your Ph is, and the water temp, and the volume of water, and what the CH of the pool water is,...then its possible that some of the calcium could precipitate out into solid particulates. If you brush the walls and the water goes slightly cloudy, then thats probably what happened. Keep the walls brushed and the pump running and it should filter out without any harm. Check your Ph and get it down to between 7.2 and 7.4 before adding the Cal Hypo or the Chlorine and that shouldnt happen.

A note though, if it is calcium particulate, you should keep an eye on your filter pressure. That stuff can exasperate the filter cleaning cycle.

Its not feeding the algae. That algae is very agressive on its own without any help. Merely a coincidence that happened to you.

Thanks Casey ,

Would the calcium buildup feed the algae ? Certainly seems to work that way ! It was the first dose of calc hypo it had ( ever I think ) and I'm not convinced I used enough , apparently there are different strengths available so it might be a weaker concentrate than I'm used to working with , also with the chems they all seem to say add water ( well product to water ) but never give how much to dilute it by ! You reckon one dose could cause visible scaling like that ?

Really appreciate all these replies guys

 

[Lankyone]

So I managed to get a sample of water via 2 different carriers to a shop that would analyse water for me , this is all I got back ! And they talked them out of buying chlorine as it was a salt pool is anything any info any more use , 5 more hours in the pool scrubbing algae in the hope there was liquid chlorine on its way ! That was yesterday , it's prob grown back this morning !!

Really appreciate all this info Dave , I've been doing a lot of reading

Cheers

Niall

 

[Casey]

You can brush til your poor arms fall off... If they don't get a steady dose of chlorine in that pool at SLAM level, it's going to be like a dog chasing it's tail.

 

[Patrick_B]

I can't add much to what Dave and Casey are telling you, but welcome to the forum. Just to reinforce, Calcium does not feed Chlorine. Sorry to hear of your troubles, but keep on this track and you'll be amazed how easy this is by the end of this summer. We don't teach anything magic here but the simplicity of how we manage pool water makes it seem like it is.

Enjoy the forum.

 

[Geelow]

I solve most black algae spot issues with a filter clean. Then slam it with tricolor through the skimmer and keep it at 30ppm for a week straight. Add some black algae kill and Brush the spots with a metal brush everyday during that week.

 

[Patrick_B]

I solve most black algae spot issues with a filter clean. Then slam it with tricolor through the skimmer and keep it at 30ppm for a week straight. Add some black algae kill and Brush the spots with a metal brush everyday during that week.

Elevating the FC and holding it there with SLAM method will do the job. Adding Algaecide of any kind is not what we would normally suggest. Some of them have terrible side effects, so we almost always discourage using them.

 

[Geelow]

Black algaecide works for me well. I can understand what you're saying though. There is so many products on the market that don't work. Thankfully I know which do. I can knock out black algae spots with my method in one day to the naked eye. It's not just the high chlorine that does it.

 

[Patrick_B]

One very important reason we don't suggest algaecides in general, is because many of them contain copper. It's great if you know what works in your pools, but please don't suggest that people use them here. Free Chlorine can do it more than adequately enough.