Having problems with Green Algae coming back over and over and.........

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
That is simply not true that operating at a higher FC at the same CYA will use the same amount of bleach. The loss is roughly proportional to the FC level for a given CYA level. If you maintain double the FC at the same CYA level you will lose roughly double the amount of chlorine and this will cost you about twice as much in chlorine cost. When you double the FC level (keeping CYA constant), you double the concentration of ALL the chlorine species -- hypochlorous acid, hypochlorite ion, and chlorine bound to CYA. The doubled concentration reacts twice as fast and breaks down in sunlight twice as fast.

While the initial dose for a phosphate remover can be somewhat costly where reducing 3000 ppm in 18,000 ppm using Orenda PR-10,000 would be (3000/10000)*(19000/10000)*$40 = $23, the maintenance dose to reduce even 1000 ppm per year would be only about $8.

So while the philosophy of not using phosphate removers and instead maintaining an FC/CYA ratio that prevents green and black algae growth regardless of algae nutrient level is simpler to explain and implement, it is not necessarily the least expensive approach. Also keep in mind that the use of phosphate removers is incompatible with using an HEDP-based metal sequestrant.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
It'll depend on what FC level keeps away algae in this particular pool. If it's only a few ppm above the normally recommended level, then that's not very much more chlorine. If it requires closer to a 15% FC/CYA level such as may be required for yellow/mustard algae, then that would be double the normal 7.5%, then that would be double. In this case, it's not yellow/mustard algae and it's an SWCG so there's hope that it doesn't require that much higher a level so just keeping the FC/CYA ratio somewhat higher sounds reasonable. Also, given that it's an SWCG, the extra cost is only in somewhat sooner SWCG cell replacement.
 

Docker_rob

Active member
Feb 7, 2015
43
Perth - Australia
did u ever get ur algae problem under control?

are u now using a preventative like polecat 60 or phos free?

Hi I did use a phos reducer as a once off treatment (Cant recall brand) to reduce my Phosphate levels as I was still getting small outbreaks even when I was keeping my FC levels within spec. (Lower end admittedly but was around 4ppm and still has signs of algae showing up)

Anyway it did reduce the phos levels but whether it was worth it I dont know. I know I could have worked around it by keeping FC levels higher but I figured it was worth a shot just to add a bit of insurance for when my FC dips down from high use etc.

Being it is my summer (and School Holidays) I have had very high bather load and have been supplementing SWG with Liquid chlorine to keep FC levels up otherwise with burn off from the Sun and the load from so many kids in the pool all day my SWG was just not keeping up.

As for the Algae - So far so good.
 

Patrick_B

TFP Expert
LifeTime Supporter
Jun 7, 2011
15,006
Midland TX
That is a primary contributor to your Algae problem no doubt, but it still equals the same problem-low FC. I'm one of the minority here that believe Po4 removers and Polyquats have a place in certain situations, but they aren't meant to be a crutch. High bather loads only mean you need to be a little more vigilant about maintaining good FC levels.
 

Enjoying this content?

Support TFP with a donation.

Give Support

squibcakes

Well-known member
Sep 20, 2015
55
QLD Australia
Interesting read Rob. Earlier you thought that the non-connected solar pipes may have been breading algae. This has got me thinking about my solar pipes which have been fitted but not connected.

I popped the end caps off the feed / return pipe and noticed a distinct bad smell. Obviously the water is stagnant.

There is no yuck coming into the pool around the solar suction fittings and return fittings but I wonder if there is a trojan army building in those pipes I should worry about.

My first thought was to pump out the water in the pipes and then possibly fit a small pump to regularly circulate the water in those pipes. Another idea would be to connect those pipes to the main pump return line.

Is this a good idea?

At this stage I'm not sure when or if we would fit solar heating to the pool but had the pipes laid for just in case.
 

Docker_rob

Active member
Feb 7, 2015
43
Perth - Australia
For me I am 99% sure the Water on my Solar pipes was not an issue.

If you can get access to them easily you could just tip a bit of liquid chlorine in at the open end from time to time to be 100% sure and even throw the garden hose in to flush them out a bit, but as I say for me (after sitting idle for 3 years) they weren't an issue and seemed the water in them was getting enough chlorine one way or another. (Mine are in use now with Solar connected )

cheers
 
Thread Status
Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.