Community

sounds like you're dealing with metal stains, especially if they are brown/black and won't scrub off. brown is usually iron, blackish is often manganese or sometimes copper if it's really dark. first thing to do is try a spot test. get a cheap vitamin c tablet (ascorbic acid) and rub it on one of the stains, if it lifts or fades instantly you've got metals. if the vitamin c does nothing, try holding a trichlor tab against a stain for like 30 seconds (wear gloves) - if that lightens it then it could be organic. assuming it's metals since brushing failed, the real fix is a stain treatment with ascorbic acid or a sequestrant product, but you gotta know your pH and chlorine levels first. you basically drop chlorine to near zero, drop pH low, add the stain remover, let it circulate, then slowly bring chems back up while adding a metal sequestrant to keep the metals suspended. be warned it's a whole process and you can make things worse if you rush. also before doing any of that, test your fill water for metals so you know if you're just gonna re-stain later.

i had this exact thing on my vinyl liner last year, drove me nuts. seconding the vitamin c test that's the tell. once you confirm its metal, don't bother with just shocking or scrubbing harder you'll make it set worse. when you do the ascorbic acid treatment, MAKE SURE you follow the instructions about not having chlorine in the pool or you'll waste your money and get weird brown water. and definitely get a good metal sequestrant, like the kind that says it prevents staining, not just a clarifier. i did it once without the sequestrant and the stains came back in two weeks. oh and after you're done, add your chlorine back in verrrry slowly or the stains will just drop right back out. like over a couple days slow.

thx both, it was the vitamin c thing - stain just vanished under the tablet. gonna read up on ascorbic acid treatment, my ph is at 7.4 right now so guess i gotta plan a weekend for this. will grab a kit with the sequestrant included, hoping i don't mess up the chlorine part lol.

when pressure stays high right after a backwash the first thing i'd suspect is channeling in the sand bed. over time the sand can clump or form little pathways the water just shoots through instead of getting filtered. try a deep clean: with the pump off, open the filter, stick a garden hose down in there on low flow and gently stir up the sand until the water overflowing the top runs clear. also reach down and feel if the sand has gotten rock-hard or mushy—if it's solidified you may need a sand change. while you're at it pull the standpipe and inspect the laterals for cracks, any sand escaping to the pool is a dead giveaway of that. after you button it back up do a rinse cycle before going back to filter, sometimes a bit of debris gets churned up and needs to settle.

was the gauge stuck before you backwashed? i had one that would read high even with the pump off til i tapped it. could just be a bad gauge. also check if you have a multiport valve and the spider gasket inside is worn, a little bypass there can send water the wrong way and mess with flow. the weak jets part makes me think it's not just the gauge tho. one more thing—if you added any clarifier or floc recently that can gum up sand pretty quick, might need a deeper clean like the other person said or even a sand replacement if its old.

thanks yall, gonna try the deep clean this weekend. forgot to mention i did use some clarifier a couple weeks ago when we opened, so that might be part of it. gauge seems fine, i whacked it and it dropped to zero when i shut the pump off. fingers crossed the sand isnt toast.

yeah that classic post-party ghost reading — looks perfect but it’s screaming for help. when you’ve got that many bodies, all the sweat and sunscreen chews through your sanitizer and drags the alkalinity down with it. first thing i’d do is get that alkalinity up with baking soda, broadcast it slowly across the deep end with the pump running, give it a couple hours to mix, then retest. you want that buffer stable before you blast chlorine or you’ll be chasing the needle for a week. for the chlorine hit, use liquid shock or cal-hypo soaked in a bucket first — do not toss acid in alongside it, ever. add the oxidizer after alkalinity’s in shape, run the pump overnight, and test again in the morning. if there’s still a combined chlorine smell or it won’t hold, you may need to give it another round, but let the numbers lead. and honestly i’d consider a partial drain if someone had a diaper fail, but that’s a whole other vibe.

sunscreen is the silent killer honestly. when my brother’s football team trashes my pool i always have zero chlorine and ph drops cause of all the oils. i do the baking soda thing first like the other reply said, but i also run my filter 24/7 for at least two days and scrub the waterline. you might see a little cloudiness kick up once the chlorine starts oxidizing all that junk, but it passes. also no swimming until you can hold free chlorine above 1ppm for a few hours — not just right after you dump it in.

thx both. this is my first season with a pool and i was about to just dump a whole bucket of shock and hope for the best. gonna tackle the alk first tonight.

Not sure the question here, but borax can be used to make the water feel nicer and also help with PH buffer - makes it not so wobbly. Just note that a heavy dose can raise PH up immediately, so dose with acid.

Dirty filter, most likely. Water will still be clear but pressure increases.

Sun burns through chlorine fast, so shock in the evening/after sundown so it works all night. CYA in the water protects it somewhat, but evening is still the move.

Algaecide goes AFTER the shock, not before — high chlorine breaks down a lot of algaecides (hence the foam). Let your FC come back down to normal, then add it if you still need it. Foam will dissipate on its own.

Yeah it degrades slowly, roughly 3-5% a month is normal and faster in hot/sunny weather. Splash-out and backwashing lose some too. Topping up mid-season is totally normal.

I swear mine disappear over the winter (9 month in mn) several years I was close to 0 after being above 30ppm

Put it in a sock in the skimmer or hang it in front of a return — takes a day or two. Don't dump granular CYA on the pool floor, it can etch plaster. And it doesn't gate swimming, you're fine to use the pool while it dissolves.

sock in the skimmer, got it. thanks

yep, sock or filter bag - drop it in skimmer or hang in front of return jet.

Yep calcium scale. Pumice stone works on tile and plaster (NOT vinyl or fiberglass), or a scale remover product. Long term keep pH around 7.2-7.6 and keep an eye on calcium hardness — high pH + high CH is what deposits it.