New Pool - Slight Green Tinge After Rain - Should I SLAM Already or am I Just Paranoid?

roamin

Bronze Supporter
May 4, 2020
19
North Florida
We've had our new pool setup for almost a week now, and it's been great. Still working to get all of the chemicals to the proper levels, but have been trying to stay on top of FC like a hawk and water has been crystal clear. I brushed the pool for the first time yesterday evening, and then we got some good rain last night and I woke up to a slight green tinge to the water this morning. I attached a before and after picture, but to me, the current state looks a little greener than it shows in the picture. From what I'm reading in other posts, it sounds like I should go ahead and SLAM the pool and not wait, but I'd love confirmation on that.

Current Levels:
FC: 4.5 (added 8 oz of LC to bump it to 6 this morning, but haven't re-tested yet)
pH: 7.6
TA: 190
CH: 175
CYA: 20

I have a SWCG but have not added salt yet, so it's not in use. I've just been maintaining the pool manually with LC. I added CYA about 4 days ago and thought I added enough to bring it up to 40 (according to PoolMath), but the level only made it to 20. I haven't added more yet because I wasn't sure how long I should wait in between doses (and I didn't want to add another 7 days of waiting to backwash the filter, since that'd end up being nearly two weeks of no backwash). I also know my TA is way too high and I have MA to add, just haven't yet because I wasn't sure about doing that while working on the CYA level.

Questions:
- According to the FC/CYA chart, it looks like SLAM level should be 10 for my pool since I'm at CYA 20 and not running the SWCG. Should I go ahead and bump it up to SLAM level now?
- Can/Should I go ahead and increase CYA now as well? Can I do that while SLAMming? Will/Won't that change what level I should SLAM at?
- Should I also go ahead and add MA to get the TA down? Can I do that while SLAMming?

All advice is appreciated! Thanks!!
 

Attachments

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
33,378
Laughlin, NV
and I didn't want to add another 7 days of waiting to backwash the filter
How are you adding your CYA? Use the sock method.

Do you have iron in your fill water? The picture shows a clear pool with a green tinge. That looks more like iron than algae. Put some paper towels in the skimmer and see if they turn brown.

Mangae the pH and TA will fall were it falls. No reason to focus on it.
 
  • Like
Reactions: roamin

roamin

Bronze Supporter
May 4, 2020
19
North Florida
How are you adding your CYA? Use the sock method.
I used the sock method (in front of a return) to add the CYA. Do I not have to wait to backwash because of that? Is that only if it's added through the skimmer?

Do you have iron in your fill water? The picture shows a clear pool with a green tinge. That looks more like iron than algae. Put some paper towels in the skimmer and see if they turn brown.
This is a definite possibility, but not sure. I would definitely say that, yes, the water is clear, just with a slight green tinge to it. After reading your comment, I remember that the manual that came with the pool said this could happen at first because of chlorine reacting to metals in the water but I guess I just freaked because it hadn't happened yet (we filled the pool last Wednesday) and the color just scared me. :) I will test with paper towels like you mentioned.

Mangae the pH and TA will fall were it falls. No reason to focus on it.
Okay, thanks. This is great news as it was in the back of my mind bothering me.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
33,378
Laughlin, NV
I used the sock method (in front of a return) to add the CYA. Do I not have to wait to backwash because of that? Is that only if it's added through the skimmer?
Once the CYA was fully dissolved from the sock, you can test it 24 hours later.

If you added 40 ppm, then that is what you have, or very close to it. Adjust your test method to get close to that result.
 
  • Like
Reactions: roamin

roamin

Bronze Supporter
May 4, 2020
19
North Florida
Thanks for your help, @mknauss. Only a very small amount of discoloration on the paper towel...not as much as I expected to see, but definitely there. Regardless, after 4-5 hours of the pump running, she's back to clear AND colorless. HUGE difference from this morning. Sorry for my panic. :LOL:

If you added 40 ppm, then that is what you have, or very close to it. Adjust your test method to get close to that result.
This is good to hear. I originally added 22 oz of CYA, which PoolMath says should've taken me to ~37ppm, so I was thinking my result of 20 on the test just couldn't be right even though I tested twice, two days apart, and came up with the same result. I know the instructions say this test is the hardest one to "get", though. The only thing that worries me a little still is that between the 30-40 mark, I can definitely still see the black dot at the bottom...it's very faint, though (and maybe since I know it's there, it's hard to "not" see?). Either way, feeling much better about where I'm at, so again, thanks for your help!!
 

Attachments

  • Like
Reactions: mknauss

kellyfair

Gold Supporter
Bronze Supporter
Jun 29, 2016
2,925
Tampa, FL
Just FYI, you don‘t have to follow a schedule to backwash your sand filter. Just watch your pump pressure, and when it rises 25%, then backwash.

For example, while I did backwash this week because I had to SLAM due to power blip that tripped my SWG and I didn’t notice for a couple of days, before this past week I think the last time I backwashed was in early May. I do use a skimmer net and change that about once a week.
 
  • Like
Reactions: roamin

kellyfair

Gold Supporter
Bronze Supporter
Jun 29, 2016
2,925
Tampa, FL
Also, when testing CYA, just fill to first line, glance in, fill to next line, glance in, and so on. That way you aren’t driving yourself nuts staring at the dot, and trying to determine where it disappears between lines.

CYA sometimes takes a day or two to show up.
 
  • Like
Reactions: roamin

roamin

Bronze Supporter
May 4, 2020
19
North Florida
Thanks, @kellyfair! I was paranoid about limiting my ability to backwash (though, it turns out I actually wasn't by using the sock method) because I wasn't sure how often I'd end up having to do it.

Update for anyone who happens upon this thread in the future...as I was explaining what happened to my wife this evening, she reminded me that the pool is sitting directly under the canopy of a huge oak tree and that the rain that comes down through it (and lands on our table and chairs) has had a dirty yellow tint to it lately. Duh. 🤦‍♂️