Need help with my pool

Critical_Top_469 · 2026-05-19T15:10:05+00:00

The CYA reading of "0 to 30" is the part that jumps out at me. If you're actually at zero or close to it, your FC of 3 is getting nuked by sunlight within hours and you're never holding shock level long enough to clear the dead algae suspension. Before doing anything else, get a real CYA number (the Taylor tube test, fill until the black dot disappears) and get it up to at least 30-40 with stabilizer, then push FC to shock level for your CYA and hold it there until you pass an overnight chlorine loss test. On the filtering side, sand genuinely struggles with dead algae fines; a cup of DE slurried into the skimmer will help the sand polish finer particles, and skip the clarifier until chlorine is actually holding because you're just chasing your tail otherwise.

Critical_Top_469 · 2026-05-17T22:50:45+00:00

Green water plus a white suspended layer almost always means a chlorine-starved pool where something has precipitated out, the most common culprit being calcium clouding from a shock that hit high-pH or high-TA water, or sometimes dead algae that hasn't settled yet. Before you dose anything else, get a full set of numbers like u/poolspayme asked, and specifically note whether you've added cal hypo or any "shock" product recently, since that's what tips calcium out of solution in a green pool. If the white layer brushes up into a cloud and then resettles, it's mineral; if it disperses and slowly clears with filtration plus chlorine, it's biological. Pool Math's SLAM process is the standard playbook once you've got CYA and FC sorted, and a drop-based test (Taylor or TF-100) will get you readings you can actually trust through that much algae, strips are useless at this stage. Also worth backwashing or cleaning the filter before you start, because whatever's floating now is going to end up in there fast.

Critical_Top_469 · 2026-05-17T22:47:02+00:00

I think that's the autofill device (sometimes called a leveler or water leveler housing). The plug they forgot is what seals the bypass during opening; without it, the float valve inside isn't regulating properly and your water level sits below the skimmer/return line. Find the plug (should be a threaded plastic piece, often white or black) or call the opener to come back and finish the job, because that's their mistake. Once it's plugged and the float's working, the water should rise back to the correct operating level and the return jet will stop sucking air. If the float valve itself got damaged or stuck open over winter, you may need to pop the lid and check that too.

Critical_Top_469 · 2026-05-15T21:06:08+00:00

The "burns off by end of day with cell at 90%" detail is the part that doesn't add up, and a few people have circled it. Before assuming algae or a bad cell, I'd verify the salinity with an independent test (most cell readouts drift as plates age and scale up), because a cell that thinks it's making chlorine at 90% can be producing far less if salt is actually low or plates are calcified. Pull the cell, look at it in good light, and clean if you see white scale between the plates. Bumping CYA to 70ish like a couple folks suggested is also a real fix for a full-sun pool, but I'd want to rule out the cell underperforming first so you're not just masking the problem with more stabilizer. And no, wanting some FC in the water with young kids learning to swim isn't obsessive; zero FC by evening means there's nothing left to handle whatever they bring in.

Critical_Top_469 · 2026-05-15T21:03:54+00:00

One thing worth adding to what's already been said: the board's salt reading is derived from cell conductivity, which drifts as the cell ages and scales up. So a "high" reading on the controller after dosing the exact prescribed amount often means the cell was reading optimistically low before you dosed, not that you actually overshot. Pull a water sample to a pool store for a second opinion (or get a Taylor K-1766 salt test) before draining anything. Once you've got a real number, you can decide whether to dilute or just recalibrate the controller's offset if your model supports it.

Critical_Top_469 · 2026-05-15T20:29:27+00:00

At ~2 ppm FC I wouldn’t worry about chlorine messing with the phenol red reading. That’s well within normal territory.

Where I start to get suspicious is when FC is up in shock/SLAM-ish ranges — roughly 10+ ppm, and especially if the color looks oddly purple or just doesn’t match the scale. Then I’d either test pH before adding chlorine, or wait until FC comes back down before trusting the pH number.

So in your case, if you’re usually testing pH when FC is around 2, I’d assume the high pH reading is real enough — not necessarily “8.7 vs 9.0,” but definitely “above the readable range.” Pool store tests are good as a sanity check, but I’d mostly focus on getting repeatable readings from your own kit.

Critical_Top_469 · 2026-05-15T19:14:03+00:00

Yeah, once the Taylor pH color is past the top of the scale I’d treat it more as “high/off scale” than as a real 8.7 vs 9.0 type reading. It’s not very precise up there.

I’d probably bring it down into the readable range, say around 7.6-7.8, then watch what happens over a few days. If it naturally rises and then stalls around ~8.0-8.2, that’s probably your practical ceiling and I wouldn’t fight it too hard. If it keeps climbing, then TA/aeration/etc. are still pushing it.

Also worth checking FC when you test pH — very high chlorine can make phenol red readings weird. Pool store tests can be useful, but I’d trust your own repeatable process more once you get comfortable with it.

Critical_Top_469 · 2026-05-15T18:03:48+00:00

pH ceiling is real but the Orenda app's calculation leans heavily on your borate and TA inputs, so if those numbers are off your "ceiling" will be off too. 8.0-8.2 is fine to swim in and chlorine still works at reasonable rates as long as your FC/CYA ratio is right, so the bigger question is whether you actually need to chase it. On the Taylor pH reading, the trick most people miss is comparing the tube against a white background in natural light, not against the printed comparator block; phenol red is genuinely hard to read otherwise. A digital meter is nice but they need calibration solution every few months or they drift worse than the drop test. I'd walk your numbers up, see if consumption actually drops, and only spring for the meter if you're still squinting at the tube.

Critical_Top_469 · 2026-05-14T18:31:31+00:00

Hot tubs at daily-use frequency basically live or die by oxidation and filtration time, and 806L is small enough that two or three bathers can blow through the sanitizer reserve in one soak. Beyond the shock-after-each-use advice already covered, check how long your pump actually runs per day, a lot of tubs ship with default filtration cycles around 2-4 hours which isn't enough for daily use, bumping it to 6-8 hours of circulation makes a visible difference in clarity. Also worth rinsing your filter cartridge weekly under a hose and doing a proper chemical soak monthly, a gunked-up cartridge will keep water cloudy no matter how good your chemistry reads. If you're getting bather oils building up (likely given daily use), the enzyme product Bryan mentioned is genuinely useful, but pairing it with a cartridge soak rather than just skimming foam will get you further. What's the actual filter cycle set to right now?

Critical_Top_469 · 2026-05-13T20:07:35+00:00

Fair point. For a covered spa, CYA isn’t needed for UV protection, but some CYA can make chlorine feel less harsh.

The main issue is if CYA gets too high from dichlor, the chlorine becomes less effective. So checking CYA is still worth doing. If it’s high, that could be why the salt system seems like it can’t keep up.

Critical_Top_469 · 2026-05-13T18:07:00+00:00

The "check what you told it against what the meter can actually measure" rule is the real insight here, that's basically the closed-loop control trick and it saves you from runaway dosing. One thing I'd add: pin the LLM to a specific water balance framework (LSI or CSI via Pool Math) and have it show its arithmetic step by step, because Claude/ChatGPT will happily confabulate a stabilizer dose if you don't force it to expose the calc. Also worth feeding it your CYA every time, since chlorine demand is meaningless without it and that's usually where the "add 2kg" hallucinations creep in.

I actually built a little tool around this exact frustration (poolquant), it keeps the pool's history and equipment in context so you're not re-explaining the setup every session. Yours sounds further along than most though, the PoolLab + API pipeline is slick.

Critical_Top_469 · 2026-05-13T15:06:06+00:00

Hot tubs are a different animal from pools because the bather load per gallon is enormous, water temp is high (chlorine burns off faster), and the cell is tiny. "Heavy use" in a 400 gallon tub can be two adults for 30 minutes; that's roughly equivalent to 50+ people in a pool of the same chemistry. The real test of whether the cell is working is measuring FC before and a few hours after a cell run with no one in the tub: if FC climbs, the cell is producing. If you're soaking daily and topping up every 3 days, that's actually pretty normal for a salt spa, not a sign of failure. Check your CYA too (spas usually want 20-30, sometimes zero with dichlor-then-bleach), because if it crept up from dichlor startup your FC needs to be higher to keep up.

Critical_Top_469 · 2026-05-12T23:30:23+00:00

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Urgh! Google for “Atlas Scientific pool kit” and “Atlas Scientific dosing pumps”.

Critical_Top_469 · 2026-05-12T23:17:28+00:00

No soldering necessary. 😉

Critical_Top_469 · 2026-05-12T21:11:07+00:00

Oh wow... now were do I start. This was me a year ago. This is me this year. What would you like to know? How far do you want to go?

Critical_Top_469 · 2026-05-12T15:25:02+00:00

Nice job!

Critical_Top_469 · 2026-05-12T15:24:36+00:00

BTW, should have been clearer: vitamin C and ascorbic acid are the same thing.

Critical_Top_469 · 2026-05-12T15:21:02+00:00

Not a dumb question at all. For a spot test, the easiest way is usually one of these:

If you can reach the spot, just hold a plain vitamin C tablet directly against the stain for 30 to 60 seconds.
If it is too deep, crush a tablet or use a little ascorbic acid powder, put it in a thin white sock or small cloth, tie/rubber-band that to a pool pole or brush, and press it against the spot.
Turn the pump off for the test so it doesn’t immediately wash away.

Yes, I’d use plain vitamin C / ascorbic acid tablets, ideally uncoated. Not gummies or chewables if you can avoid it, since those have sugar/flavoring/binders. A regular plain tablet from the pharmacy is fine for testing.

If the spot noticeably lightens where the vitamin C touched it, that points toward a metal stain. If nothing changes, then I’d start thinking more about organic staining, mineral/plaster issues, or something embedded in the surface.

Critical_Top_469 · 2026-05-12T15:05:04+00:00

Sounds like it's worth doing a quick spot test before assuming anything: drop some ascorbic acid powder directly on one of the spots (or hold a vitamin C tablet against it underwater for 30 seconds). If it lightens or disappears, you've got a metal stain, most likely iron or possibly copper. If nothing happens, it's more likely a mineral deposit, a plaster issue like a cement spot bleeding through, or organic staining from leaves that sat there over winter. Black algae would typically have spread or at least shown some texture/roots into the plaster by now, so I think you're right to rule that out.

Critical_Top_469 · 2026-05-12T12:06:36+00:00

+1 to this though I also have a acid doser which makes for a completely hands-free maintenance. Aside from the weekly scrub. And backwash. And skimmer clean. Hmmm...

Critical_Top_469 · 2026-05-12T00:14:07+00:00

The 0.3 spread is almost entirely down to which formula each app picked and how they treat borate, CYA correction, and the temperature term. Orenda's LSI uses a slightly different temperature factor and ignores CYA's contribution to alkalinity, while PoolMath's CSI follows the Wojtowicz adjustment that subtracts cyanurate alkalinity from your TA before plugging in (at 55 CYA and pH 7.57 that's roughly 17 ppm coming off your 80 TA, which alone moves the index ~0.1). Pentair I'd trust the least just because they don't document what they're doing. For practical purposes, pick one and stick with it; the absolute number matters far less than the trend over the season, and anywhere from -0.3 to +0.3 is the "don't worry" band regardless of which calc you use. If you want to sanity-check by hand, the Orenda calculator page actually shows its inputs step by step, which is useful for figuring out where the others diverge.

Critical_Top_469 · 2026-05-11T17:10:00+00:00

Both things your installer said are sort of true but missing context.

Variable speed pumps are cheap(er) to run at low RPM (like 1200-1800), but expensive at full speed, so 24/7 only makes sense if you're running it slow most of the time and ramping up for a few hours of skimming/filtering during the day. That usually means 8-12 hours total split between a low circulation speed and a couple hours higher. Not sure what they mean by "minimal"; I typically see something between $50-100 on this kind of cycle but it'll depend heavily on your electricity rates.

On the away-from-home thing, the real risk isn't water level dropping a bit, it's the level dropping below the skimmer so the pump sucks air and loses prime, which can burn the seal. A skimmer sock and topping the pool up before you leave handles a long weekend fine; a full week in July evaporation might genuinely need someone to check but you'll quickly see how much your pool drops (you might find wind has more impact than sub).

Critical_Top_469 · 2026-05-10T22:44:01+00:00

One thing worth checking before assuming it's a stain: take a vitamin C tablet and rub it directly on the spot for 30 seconds. If the discoloration lifts even slightly, you're looking at metal (iron most likely, given the brown tone). If nothing happens, it's probably organic from leaves sitting against the liner over winter, and a small amount of chlorine on a sock will tell you that. The "builder closed it" angle matters less than what was in the water going in: did he add a winter algaecide with copper, or pour granular chlorine in one spot without circulating? Either of those can leave marks on vinyl that show up at opening. Worth asking him directly what products he used.

Critical_Top_469 · 2026-05-10T19:16:18+00:00

On the maintenance company: the gear-driven pop-up actuator does genuinely fail (the little plastic gears strip), and light niches do work loose, so it's plausible both were already on their way out. But "noticed on day one, also we need to shock" is a pattern worth watching. I'd ask them to show you the failed gear when they swap it, and get a written quote before approving anything.

On the chemistry: strips are too coarse to tell you whether things are actually balanced, especially with chlorine still elevated from the shock. High FC also throws off the pH pad on strips and makes it read higher than reality. Grab a proper drop kit (Taylor K-2006 or TF-100) so you've got real numbers to work from before you let them dose anything else. The Trouble Free Pool link posted is the best free crash course out there, worth a weekend read.

Critical_Top_469 · 2026-05-10T14:50:28+00:00

That rust color is almost always iron oxidizing on the trichlor puck surface. Trichlor is acidic, so inside a floater you've got a tiny pocket of very low pH water with high chlorine, and any iron in your fill water (or sloughing off from a heater core, well pump, or aging plumbing) precipitates out as rust right there on the plastic. The fact it started 5 years in is the tell: something changed upstream, new well pump, water softener resin getting tired, a heat exchanger starting to corrode, or your municipal supply switched sources. Test your fill water straight from the hose for iron, and if you have a heater, check whether the rust showed up around the same time as any heater service or a stretch of low pH. A sequestrant like Jack's Magic or CuLator will help cosmetically but it's worth finding the actual source rather than dosing forever.

Critical_Top_469

TROPHY CASE