Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 15 of 15

Thread: Is some algae to be expected?

  1. Back To Top    #1

    Join Date
    Nov 2013
    Location
    Elkridge, MD
    Posts
    81

    Is some algae to be expected?

    I previously had some issues with algae this season (first year owning the pool), but I SLAMed it and cleared it up. It's been a month now and the water is still crystal clear, the FC has stayed at ~6ppm with no issues, CC is around 0, and no dips in chlorine levels from what I've seen (SWG pool). It's a fairly large pool, 17' x 40' x 12.5 (deepest end), and only has 2 return jets. I've angled them to try to get good circulation of the water. I also scrub 1-2 times a week, sometimes more, depending on if I'm outside already to swim.

    Anyways, I've noticed that there are spots around the pool that tend to get some small algae growth during the week. Around the stairs (built in) there are some spots that get a little green, when we were swimming a few days ago some of the walls had a very slight slime feeling to them. Some of the nooks and crannies, or chips in the plaster, and in the lattice work under the deep-end ladder, seem to get slight algae growth in them. I focus on these areas when I scrub the pool, but I was wondering if this is normal.

    It seems to be in places where the water isn't circulating well to, but the chlorine levels are high enough and the CC has never been more than .5 (the test barely gets enough pink tint to require a single drop to turn it back clear). The scrubbing is supposed to help circulate the water some, and I assume swimming has similar effect as it's getting moved around by people instead of just where the jets send it to. So is there something different I should be doing? Is this normal, as long as it doesn't get out of hand and the chlorine levels stay steady, it's fine? After my previous issues and SLAMing the pool for weeks, I'm trying to avoid having another issue this season.
    33,000 gallon gunite pool and Spa (in ground), SWG
    Sta-Rite System 3 Modular Media Filter (300 Sq. Foot cartridge filter)
    Jandy Lite2 Natural Gas Pool and Spa Heater

    Maryland, USA

  2. Back To Top    #2
    Mod Squad tim5055's Avatar
    Join Date
    May 2014
    Location
    Columbia, SC
    Posts
    8,495

    Re: Is some algae to be expected?

    No if FC is kept at the proper level in relation to CYA the no algae should grow. Can you post recent numbers including CYA.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

  3. Back To Top    #3

    Join Date
    Nov 2013
    Location
    Elkridge, MD
    Posts
    81

    Re: Is some algae to be expected?

    pH 7.5
    FC 6.5
    CC 0
    CYA 50
    CH 280
    TA 130

    I have an in ground spa as well, though I shut it down last month while I was SLAMing the pool (one problem at a time). I am just about to recombine the 2 again, at which time I expect my numbers to change some as the pool water mixes with the fairly fresh water in the spa. It's a SWG pool, so I was going to raise my CYA another 10-20ppm still. Someone mentioned not to bother with the CH as it would require a lot of water replacement. TA is high as well, but again I was told not to bother as long as I kept my pH in check. I'll be doing final chemical adjustments once I get both systems working together again. My FC is also technically higher than it should be for my CYA level, but I was being cautious and figured better safe than sorry and keep it higher to be sure no algae returned.

    I've done the full set of checks every week for the last 5 weeks and I've received the same readings every time. My pH got closer to 8 a few weeks back and I used muriatic acid to lower it back down. It's also been fairly dry lately so I've been adding some water using the hose to make sure it stays at the proper level. When doing so, I've turned my SWG up to super-chlorinate.
    33,000 gallon gunite pool and Spa (in ground), SWG
    Sta-Rite System 3 Modular Media Filter (300 Sq. Foot cartridge filter)
    Jandy Lite2 Natural Gas Pool and Spa Heater

    Maryland, USA

  4. Back To Top    #4

    Join Date
    Oct 2013
    Location
    Chapin, SC
    Posts
    1,141

    Re: Is some algae to be expected?

    Your ch is fine, don't worry about it. What I'd be concerned of is all that uncirculated water in the Spa. No telling what kinda nasty stuff is lurking in there. Yes, your cya is ok except for the swg part. It really needs to be 70-80.
    Pool size: 24000gal inground Vinyl-Taylor k-2006 and k-1766 test kits and-speed stir
    Intermatic P1353ME digital timer w/freeze sensor
    CircuPool Si-45 SWCG System
    Polaris 280 vacuum/Polaris PB4-60 boost pump
    Pentair IntelliFlo VS 3hp Pump--Pentair sand filter

  5. Back To Top    #5

    Join Date
    Nov 2013
    Location
    Elkridge, MD
    Posts
    81

    Re: Is some algae to be expected?

    Quote Originally Posted by timerguy View Post
    Your ch is fine, don't worry about it. What I'd be concerned of is all that uncirculated water in the Spa. No telling what kinda nasty stuff is lurking in there. Yes, your cya is ok except for the swg part. It really needs to be 70-80.
    I was waiting to raise my CYA further until I got the spa cleaned back up and working again. Since my FC levels have remained level with the CYA at the level it's at now, it was lower on my list of things to do. And the spa was getting mosquitos in it, but I've since killed them and shocked the hot tub and refilled it, cleaned it, and begun filtering the water.

    So if this small amount of algae isn't normal, is it because the FC is somehow too low? With my current CYA level, my FC is also supposed to be lower too, so I feel like it should definitely be killing this stuff. I figured if it's 6.5ppm around the normal circulated parts, and probably higher closer to the return jets, and likely somewhat lower around the less circulated areas (like the steps and nooks), it would still be around 5ppm, which is supposed to be enough to kill algae. I can take some readings of the water near areas I get algae at and test the FC/CC there if it helps diagnose anything.
    33,000 gallon gunite pool and Spa (in ground), SWG
    Sta-Rite System 3 Modular Media Filter (300 Sq. Foot cartridge filter)
    Jandy Lite2 Natural Gas Pool and Spa Heater

    Maryland, USA

  6. Back To Top    #6

    Join Date
    Nov 2013
    Location
    Elkridge, MD
    Posts
    81

    Re: Is some algae to be expected?

    Another oddity that may help knowing, I don't actually know how many gallons are in my pool. I posted my dimensions above, but when I got the pool inspected before I moved in, they calculated it at 25,000 gallons including the hot tub. I used those numbers when I did the SLAM and added in the chemical amounts. I used those numbers when I increased my CYA levels. It seemed spot on because it got my FC exactly to the levels it said it should be when I added the chlorine. If the pool math said "add 60oz to raise the FC 2ppm," I did so, tested it an hour later, and it was exactly where it said it'd be.

    So here's the oddity. I started doing calculations of how many gallons the pool should have based on the dimensions (using pool math and just volume calculations, converted to gallons) and it seems closer to 40-42,000 gallons (including the spa). So I'm confused as to what volume is correct. If it's actually 40K gallons, the amounts of chemicals I put in would not have raised levels correctly. If it's actually 25K gallons, why do all the calculations not add up to that?

    I originally thought that maybe because of this miscalculation, I hadn't raised the FC enough during the SLAM, except that the tests don't care about pool volume, just ppm of FC and CC, and those all read the proper amounts. So I'm still unsure which calculation is actually right, or if that matters since we're talking about ppm (ratios).
    33,000 gallon gunite pool and Spa (in ground), SWG
    Sta-Rite System 3 Modular Media Filter (300 Sq. Foot cartridge filter)
    Jandy Lite2 Natural Gas Pool and Spa Heater

    Maryland, USA

  7. Back To Top    #7

    TFP Guide

    Kiss4aFrog's Avatar
    Join Date
    May 2013
    Location
    Hudson, WI
    Posts
    2,602

    Re: Is some algae to be expected?

    Quote Originally Posted by ndakotaninja View Post
    So if this small amount of algae isn't normal, is it because the FC is somehow too low? With my current CYA level, my FC is also supposed to be lower too, so I feel like it should definitely be killing this stuff. I figured if it's 6.5ppm around the normal circulated parts, and probably higher closer to the return jets, and likely somewhat lower around the less circulated areas (like the steps and nooks), it would still be around 5ppm, which is supposed to be enough to kill algae.
    I think you are confusing the SLAM level which will kill algae with the maintenance level which should prevent it or keep it in check but NOT KILL it if it's allowed to start or introduced into your pool (swimsuit, pool toy, ...).
    That is the whole reason that maintaining a shock level is necessary to eliminate algae. It's also why you really need to keep above the minimum FC level for your CYA to keep algae from coming back. You may have allowed the stagnant water of the spa to contaminate the pool. Don't know, just a guess where it might have come from.

    If using the 25K is what works for doing adjustments I'd go with the 25K.
    '70s IG Vinyl 32K gal, Lazy L, Hayward SuperPump 1.5hp 120V, S240 Sand Filter W/DE
    Solar Blanket, Well Water, Borax Added, TF-100 tester. ? too cold
    1979, 275gal Conway Emerald Spa P-100-2, ES-2 Spa Pack, bromine floater, indoor
    TF-100, Best test kit - TFTestkits.net
    Please help keep the lights on, become a TFP Supporter!

  8. Back To Top    #8

    Join Date
    Oct 2013
    Location
    Chapin, SC
    Posts
    1,141

    Re: Is some algae to be expected?

    Until if and/or when it doesn't. Then you'll be rethinking your capacity.
    Pool size: 24000gal inground Vinyl-Taylor k-2006 and k-1766 test kits and-speed stir
    Intermatic P1353ME digital timer w/freeze sensor
    CircuPool Si-45 SWCG System
    Polaris 280 vacuum/Polaris PB4-60 boost pump
    Pentair IntelliFlo VS 3hp Pump--Pentair sand filter

  9. Back To Top    #9

    Join Date
    Nov 2013
    Location
    Elkridge, MD
    Posts
    81

    Re: Is some algae to be expected?

    Quote Originally Posted by kiss4afrog View Post
    I think you are confusing the SLAM level which will kill algae with the maintenance level which should prevent it or keep it in check but NOT KILL it if it's allowed to start or introduced into your pool (swimsuit, pool toy, ...).
    No, I've already SLAMmed the pool, killed the algae, added my CYA, and then allowed the FC level to drop back to the normal range. Although, as I mentioned, I've technically not let my FC drop completely to the 'normal' range for my CYA, it's still slightly higher because I was going to work on SLAMing the spa and wanted to make sure I had a buffer in case of contamination. However, it took me a month to get to the spa, and the algae has shown up in the pool during that time.

    As to where it came from, I'm not sure. Supposedly keeping my FC at 6.5 should be more than enough to prevent any new algae introduced to the pool to begin growing. The spa water was completely separate from the pool water and never mixed while it was untreated. The algae I've seen in the pool has been appearing for the last 3 weeks or so, and after swimming/heavy rains/etc I've made sure the FC level has remained at 6.5. Which is why I was asking if it was normal to see some small amounts of algae growth, because it's been par for the course with my pool, even with properly balanced/treated water.

    And just to point out, the CC has stayed at or near 0 the last month, and the algae I see is very small amounts, but something I still wouldn't expect to see. The pool is pretty old (20+ years), so not sure if it just needs to be resurfaced or something to smooth it out and provide less places for algae to settle.
    33,000 gallon gunite pool and Spa (in ground), SWG
    Sta-Rite System 3 Modular Media Filter (300 Sq. Foot cartridge filter)
    Jandy Lite2 Natural Gas Pool and Spa Heater

    Maryland, USA

  10. Back To Top    #10

    Re: Is some algae to be expected?

    I think your theory about lack of circulation is correct. The FC can drop in nooks and crannies as it fights an algae growth attempt. If the water does not circulate to add chlorine-filled water, the algae will win and grow in those low circulation areas.

    How much to worry about it is an aesthetics and effort question. The presence of algae is not a health issue. (It can be a safety issue if it obscures visibility of swimmers, but that is not what you have going on.) If you don't want it there, you will need to continue to brush/scrub it away. Resurfacing will likely help with the algae that is "hiding" in the indentions in the plaster, because chlorine won't be forced into those indentions as easily as passing along a smoother surface.

    How often and how long are you running the pump and SWG?
    Outdoor 14,000 gallon IG plaster pool built in 2000 with spillover spa, 2 hp WhisperFlo pump with MagneTek motor, Sta-Rite cartridge pool filter with 300 ft2 filtration area and 0.33 gpm/ft2 filtration rate, Aquabot Rapids 4WD robotic pool cleaner, Raypak digital gas heater, and Intermatic mechanical timer located in the Dallas-Fort Worth metroplex

  11. Back To Top    #11

    Join Date
    Jun 2014
    Location
    Boca Raton, FL
    Posts
    101

    Re: Is some algae to be expected?

    What is your schedule to run the swg? (maybe a timing issue) How often are you swimming (added circulation)?

    Working along the premise that is is a circulation issue, I would take a sample from the algae prone area immediately before the swg turned on to see if there is a shortage of FC or higher CC and compare those numbers to those from your normal testing source.
    16x32 DiamondBrite kidney, 12,500 gal. (circa 1985) 3/4hp Hayward SII, Harmsco BF84, Taylor K-2006, Hayward SwimPure Plus / Tcell-15
    Boca Roton, Fl. USA.

    prior 17k gal. vinyl, Sand filter

  12. Back To Top    #12

    Join Date
    Nov 2013
    Location
    Elkridge, MD
    Posts
    81

    Re: Is some algae to be expected?

    I will check when I get home on the exact timings, but I set my pump up to run in the early morning (I think 5am-11am) and then again in the early afternoon (3pm-8pm), giving it about 10-12 hours a day, but not running during the 'peak' hours for my electric bill. I'm still trying to balance the correct SWG % with the right amount of runtime to keep my FC balanced. Right now, as I said, the FC is staying high, so I've been slowly dropping my % output. The next thing I can do is adjust the runtimes. Been busy, so only swimming about 1-2 times a week in the late afternoon/early evening, while the pump is running.

    I have taken water samples right next to algae spots and tested those and it seems to be in the 6-7ppm range, even during mid-day, sun is out, and pump isn't running, so I wasn't sure how it would be growing and assumed it normal.
    33,000 gallon gunite pool and Spa (in ground), SWG
    Sta-Rite System 3 Modular Media Filter (300 Sq. Foot cartridge filter)
    Jandy Lite2 Natural Gas Pool and Spa Heater

    Maryland, USA

  13. Back To Top    #13
    Patrick_B's Avatar
    Join Date
    Jun 2011
    Location
    Midland TX
    Posts
    15,001

    Re: Is some algae to be expected?

    If you have green in the pool, you have, or have had a lack of proper FC at some point or points. There is no other explanation, there is no argument. The ONLY thing that allows Algae to grow is a lack of proper FC.

    You may never have killed it all with a correctly done SLAM procedure, but whatever the case, this is the reason. Once you kill it all, and keep the FC correct ALL the time, this problem will go away. If you relent and let it slip, you will have Algae return to your pool.
    TFP Moderator
    Essential Links:
    ABC's Of Pool Chemistry, Test Kits, SLAM Your Pool
    28K Gal IG FreeForm, CLI Quartz, Pentair 36"SF & VS Pump, Dolphin M5, Rheem

  14. Back To Top    #14

    Join Date
    Nov 2013
    Location
    Elkridge, MD
    Posts
    81

    Re: Is some algae to be expected?

    The only way that could be the case, Brushpup, is if the test kit wasn't giving me correct readings. Since I've SLAMed the pool (according to the SLAM guide and with no visible algae showing, and cc at 0), the FC has remained at or above 6ppm. It technically should be lower since my CYA is also lower right now, but since I was also seeing algae appear again, I didn't want to let it get too low.

    The only thought I had was my pH has been higher than usual (7.8-8.2 or so), and I started lowering it with muriatic acid, and it's now down around 7.6. I've also noticed a lot of new staining on the pool that's a dark metallic (almost green) color that I first thought was algae. I thought maybe the high pH caused the metals in my heater to get into the pool and cause the stains, wasn't sure if it'd have any effect on algae growth.

    The algae that I'm seeing is in the nooks or crannies, like on the stairs, that may not get direct chlorine, but again, even in those hard-to-reach places, I've tested and it's still over 5ppm FC, which should be enough. And to go with that, the cc has been <.5 or 0 ppm for the last 6 weeks, during which time the algae has grown. It's not very obvious, it dissipates when I scrub it, only to reappear a few days later in the same spots.
    33,000 gallon gunite pool and Spa (in ground), SWG
    Sta-Rite System 3 Modular Media Filter (300 Sq. Foot cartridge filter)
    Jandy Lite2 Natural Gas Pool and Spa Heater

    Maryland, USA

  15. Back To Top    #15

    Join Date
    Oct 2013
    Location
    Chapin, SC
    Posts
    1,141

    Re: Is some algae to be expected?

    Have you done an OCLT recently?
    Pool size: 24000gal inground Vinyl-Taylor k-2006 and k-1766 test kits and-speed stir
    Intermatic P1353ME digital timer w/freeze sensor
    CircuPool Si-45 SWCG System
    Polaris 280 vacuum/Polaris PB4-60 boost pump
    Pentair IntelliFlo VS 3hp Pump--Pentair sand filter

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •