Algae or not?

[kraftchick]

I've been working through this for awhile and decided to finally post to get some advice/help. I am a new Intex 18' Ultra Frame owner and have worked through most of my problems through the advice on this forum. I have taken the critical piece of advice and bought the TF100 test kit. I've been doing some testing for about a week and a half now and not sure what is going on. Through using the Pool Calculator, I've added specific levels of bleach, borax and baking soda to get to these numbers:

FC 2.5
CC <.5
Ph 7.5
TA 80
CYA 30

Water is clear, but I seem to keep getting some sort of "fall out" that collects on the bottom, and I'm wondering if it's algae or not. There is a tree limb hanging over this pool that does drop a lot of "stuff" in the pool, but I'm wondering if this is something else. It is brownish colored, and vacuums up easily, but it keeps coming back...almost daily. It seems "powdery", as you can waft by it with a brush or something and it will dissipate into the water. I do have the Intex SWG, and I've been working on when and how long to run it to keep FC level up through the day (most of the pool is in sun the whole day). I've consistently kept CC levels at or below .5 ppm according to TF100 tests. Does the CC being at or below .5 ppm rule out that this is an algae problem? Or is it still possible to have algae with correct CC levels, and clear water. Wondering if it needs to be shocked? I did do some overnight FC loss testing, and at first it was more than 1 ppm, but with the addition of the bleach, raising the FC level, and getting the SWG running time more dialed in, I've started to be able to keep it at 1 or less overnight. Right now my SWG schedule is 7 hours beginning at 8:00am....not sure whether I should run it at night or the day, but the thought process is that I would "produce" FC throughout the day, giving it a more steady level throughout the night....advice on this would be fine too.

 

[frogabog]

You will want to add more CYA to bring it up to the recommended level for a SWG pool. 70-80ppm is what is recommended although I believe 60 also could work ok.

SWG people will verify if it's 60-80 or 70-80 that works best w/SWG.

I also imagine that the dust you're seeing is actual dirt because dead algae will get picked up by the filters eventually. The Intex filters don't want to catch that fine non-organic dirt stuff, it's troublesome for me as well and incredibly difficult to vacuum because it goes right through the vac filters too.

You're on the right track for CC and OCLT results, I would not necessarily assume you're still battling organics with those results. I vote for dirt... plain old boring dirt falling out of the air and settling on the pool floor intended to pizz you off. :~}

 

[kraftchick]

Frogabog....thanks for the CYA advice...I've wondered if I should bring that up or not, but wanted to "hear" it from the experts first. So by doing that, the chorline produced by the SWG will be more efficient? The thing that I haven't yet been able to figure out is what the FC level should be maintained at, and what part of the day I should be doing my testing. Seems like evening after the sun isn't on the pool...that way I'm getting a more accurate picture of what is happening to the FC throughout the day. Maybe I should be running the SWG cycle at night to boost the FC for the next day?

 

[linen]

Regarding CYA levels for the intex swcg...the intex seems to run fine at lower CYA levels than typically recommended in the generic "Water Balance for SWG" section of the pool school. I would think 50-60 ppm of CYA might be a good place to start.

 

[frogabog]

I test whenever I feel the need, but the test I rely on is the end of day test that tells me how much chlorine to add to prepare for the next day. I do not always test at the end of the day, sometimes I guess. But I also have a general idea of the conditions that cause me to loose certain amounts of chlorine every day as well (sun, rain, swimmers, falling leaves etc.).

I guessed for the past two days and didn't even use measuring cups for dosing. I was too tired to add chlorine one night after an all day wedding, put extra bleach in the next day w/o testing cuz I left my kit in the truck and was too lazy to get it out, and found the pool at 1.5ppm last nigh once I bothered to test. It doesn't always work out this guessing stuff if you alter from the daily routine... but most of the time it is fine. Knowing your pool after a few weeks of vigilant testing gives you room to guess once in a while though, you'll figure it out.

If you enter your CYA number in the now column in the pool calculator, at the bottom it will adjust your recommended levels. SWG levels are lower than non salt pools, but it's a constant level rather than a target and minimum. Changing CYA levels in the now column will change these results btw. I believe that you can turn the SWG off overnight and expect the chlorine level to remain steady till the next morning. Assuming of course that there's nothing in the pool for the chlorine to attack. So testing for CC might be something you'll want to do regularly till you are comfortable knowing what the SWG produces for you.

 

[duraleigh]

I also imagine that the dust you're seeing is actual dirt because dead algae will get picked up by the filters eventually.

Not necessarily. I have often seen dead algae that was heretofore invisible in my pool accumulate on the bottom of my pool in the low spots. It usually just sits there until the vac picks it up....it does not stay in suspension to be taken in by the filter.

If it is absolutely essential that you know which it is, the only surefire way I know of is the OCLT test. Your FC history would also indicates it is algae because your FC has been low in the past.

I would probably suggest just making sure your FC is held ABOVE normal for at least 48 hours and see if the "fallout" stops.

 

[kraftchick]

Ok...so here's more info: just tested the FC level...it was about .5. So I added the rest of the bleach I had on hand, which measured approx. 57 ounces. According to the pool calculator, this should bring me up to an FC of 4. I'm going to let it "churn" for about an hour then I'll measure again to get the actual FC level. I will then check it in the morning to see how much is lost overnight, and post the results. I thought it was interesting this evening (9:15pm) that my FC was only .5....after the SWG had a 7 hour run that started this morning at 8:00am. I guess the lower CYA level is to blame?

 

[dmanb2b]

Likely the CYA being too low . I run my CYA around 60 with an older (stronger) intex unit and it only runs 3-4hrs per day on a 24' round.

I would first confirm you can pass the OFCLT. If not, do not raise CYA until you are done shocking. Raising CYA just makes the shock cycle more difficult. If you do pass the OFCLT, then add enough CYA to get to 60ppm and you should see FC starting to hold.

 

[kraftchick]

Dmanb2b...once I get this resolved, I'm curious what the FC level should be ongoing. The PoolCalculator shows that for a SWG pool, it should be 2 on an ongoing basis...that seems low....or is that the minimum it should be allowed to get to at the end of the day? What time of day do you run the SWG...just curious if it should be at night to "boost" it overnight, ready for the sun to do it's work during the next day...or should it be run during the day to try to keep the level throughout the day?

 

[dmanb2b]

Correct, 2ppm is the minimum. With CYA at 60, I keep my FC at a 4ppm avg. My pump and SWG run from 10am-4pm, with the SWG usually running from around 10:30-2:30. If I test my water befor the SWG kicks off, it usually will measure around 3ppm and by 3pm it is at 5ppm, by dusk it's at just about 3-4ppm.

I'm on my third year using the above and have only shocked 3 times, at opening each year, ensuring I pass the OFCLT. Your milage may vary, depending on location, sun exposure, temps, etc :lol:

The key to BBB or SWCGBB is a good testkit, like the TF100 and measuring your chemical levels until you learn how your pool behaves and ensuring your FC does not fall below that 2ppm minimum

 

[kraftchick]

That's the experience I was looking for...thanks! Checked the FC a few minutes ago...bypassed 4, it's at 6.5 (TF100 results)....will check in the morning and post to see what overnight FC loss is.

 

[kraftchick]

This morning, FC was at 6, so I only lost .5 overnight. Does this mean I am good, and don't need to shock? Water looks good and clear, but still the "fallout". So now maybe the trick as suggested is to keep the FC higher than normal for awhile to see if the stuff in question reduces. I have not ran the filter or SWG yet today. I should be able to get by the house around 1:00 today and will recheck the FC, find out what the daytime loss has been at that point, and possibly crank up the SWG for awhile to maintain FC throughout the day/evening. Then check FC again this evening. How's that sound?

 

[Bama Rambler]

What about CC's? If they were .5 or less you're good. I would go by and turn the swcg on.

 

[kraftchick]

Yes the CC was .5 or less....so, seems pretty good. I was able to check the FC at 1:30 this afternoon...was down to 4, and CC was still at or less than .5...full sun today. I turned on the SWG around 2:00 for a 5 hr run. Just checked the levels at 10:00pm...FC is between 3.5 and 4, and CC is still .5 or less. So if shock is not required....should I just do another dose of bleach to get the FC up again to maybe around 6, let that go through tomorrow like I did today (with an SWG cycle tomorrow of course), and then tomorrow evening start working on bringing up the CYA to more like 60?

 

[dmanb2b]

Sounds like a plan

 

[kraftchick]

Didn't have anymore bleach to add last night, so I ran the SWG through a 3 hr. cycle which brought the FC up to 5.5. Thinking that the full sun again today would take a toll on the FC, I kicked off the SWG again before leaving for work for another 4 hr. cycle this morning. Hopefully that will be enough throughout the day to keep FC from dropping too low. I will pick-up some bleach and CYA after work and begin to administer it. Thanks to all that have helped and replied to my questions. I will post an update on whether or not this has resolved the "fallout" stuff.....I did notice this morning that I didn't really see any of it, and usually by morning I see quite a bit of it settled on the floor.