Hi, I'm Zach, I'm a 22 year old mechanic/industrial electrician and I just started the job I always wanted in the engineering department at a company I really like a couple months ago.
Among other things I am now in charge of 3 indoor, chilled (58°F-65°F) extrusion cooling trough systems; I have 2 separate systems at the North Carolina location using well replacement water - A single system at the Georgia location using city replacement water. The 2 Locations are about 30 miles apart. In total there are (28) 1-2 hp circulation pumps with a mixture of brass, stainless, and cast impellers (28) satellite tanks (2 per extrusion line) (3) main tanks each with 4 hp main line pressurization pumps (1 per system) and we have all stainless steel tanks, troughs, and heat exchangers, all plumbing is PVC. Some satellite tanks are heated to a maximum of 90°F when running certain product.
I am here to see if I can get some input from the impressively helpful members of this forum on why the large system that feeds lines 1-7 at the NC location is so disgustingly full of brown algae. The line 8 and 9 water system is as clear as the cleanest pool you've ever seen. The 5 lines at the Georgia location are the same- perfect. We don’t do much more than put a piece of one of those pucks (I think I saw them called trichlor on this site?) in each of the clean tanks as well as sprinkle a little granulated chlorine in.
My problem is there has never been any rhyme of reason to the adding of these chemicals on the big nasty line 1-7 system, we’ll just call it the big system. On its very best day it looks like water out of a particularly dirty lake, greenish brown, on its worst... we'll get to that. None of the previous care takers even know what CYA is let alone that it is in the trichlor pucks they love so much, and neither did I until I started reading pool school and some of the threads on this site. They told me in the past that when the big system got bad (and when I say bad I mean most people are afraid to touch the water when they see it, it looks like something out of a swamp horror film) they would just start putting trichlor tablets in the tanks (all 15 of them) and dumping granulated chlorine in them. Sometimes each of these 100-200 gallon tanks ended up with 2 or 3 trichlor tablets in them, so I’m thinking that even though they were putting chlorine in as well, the amount of CYA had to be way higher than the what it should have been for the FC level at that time. After all they thought the tablets were just slow release chlorine LOL. This almost always ended up in failure and they just had to evacuate the system (but leaving the tablets in the tanks with around 10 gallons of water in each) vacuum the algae off the sides of the tanks and out of the troughs, change the filters, and backwash the sand filter and replace with new water. I think they replaced the sand once 5 years ago. Another problem is the whole system has never ever been evacuated because that would involve coming in late Saturday evening since we are not allowed to work Sunday, and there’s no way we could shut all the production lines down during the week just to clean the tanks, because they’d be losing like $10k per hour, and they have to have water to run. So it’s always been evacuate and vacuum one tank at a time, then fill it back up with the nasty water. Only other thing I can think of to add is keep in mind we have no sunlight, very few windows (like next to none where the water is) and all fluorescent lighting. I read somewhere 8 hours of exposure to fluorescent lighting gives you the UV radiation of being in the sunlight for 1 minute… I know I’m not a homeowner with a pool which is kind of the point of this site, but I don’t know where else to turn. I am trying to figure out where to get some test strips to find out what my CYA levels are and I’m going to go from there, but if anyone else thinks they can help I am open to all suggestions. I have found in my research that chlorine levels above 2 ppm are not very good for our aluminum shivs (rollers) nor the cast iron pumps so the the end goal is to have clear and algae free water in the big system like the other systems while keeping FC levels below 2 ppm, I do know that in order to get clean I'll probably have to raise it above that but we gotta do what we gotta do. Thanks for reading this terribly long explanation and for all the help I’ve gotten from the write ups on pool school, this site is really well put together!
Any questions you have that can help you help me just ask away, if I don't already have an answer Ill write them down and find out what I can the next day. I tried to cover what I knew as best I could but I'm not the best writer in the world so if something need more explanation I'm glad to do it.