Could this be algae, or just dirt?

[riny]

These snaps from my security camera were taken less than 12 hours apart. On Saturday morning we were in the pool for about 3 hours and the water was perfect. I happened to test it in the morning and my pH was a little high (I'm fighting with high TA) so I added my weekly dose of MA after we were done swimming. The chemistry was perfect otherwise.

On Saturday evening we had a rain storm of biblical proportions. The pool overflowed and there was probably a lot of runoff from the yard/patio that went into the water. On Sunday morning, I woke up to this green/brown swamp.

I immediately went up to SLAM level and I'm going to attempt to stay there until the water is clear again. It's a little tricky because my CYA is already at 60+, but I used liquid to start and I think I can use my SWG to maintain SLAM-level FC. My question though: am I just looking at dirt here which was washed into the pool by the storm? Or is it possible for algae to have grown in this short a time? Is a SLAM the right course of action?

 

[mknauss]

Hard to say. You do not share Poolmath logs so we do not know the chemistry history. It should be primarily dirt if you kept your FC properly in the target range for your CYA.

 

[riny]

Oops, I'll have to see how to turn on the logging. Here are my readings from Saturday morning:

pH 7.5
FC 4
CH 200
TA 110
Salt 2700
CYA 60

If the rain were to throw the chemistry out of whack or dump a bunch of dirt into the pool, how long would it normally take for algae to start growing?

 

[mknauss]

As it appears your environment around the pool is pretty rich in organic matter, algae can start pretty quickly. Runoff from the surrounding area should never get to the pool. That is poor drainage design. So if you had runoff into the pool, then treat it as algae and follow the SLAM Process

First order of business is to improve drainage.

I would also encourage you to consider a higher FC target. At least 6-7 ppm.

 

[riny]

I would also encourage you to consider a higher FC target. At least 6-7 ppm.

I trust you on that but can you tell me why? The chart says for an SWG at with CYA = 70, FC target is 5. I can easily bump up the runtime and maintain 6-7 but what do you know that's not reflected in the chart?

 

[mknauss]

The chart is for the average pool. Some areas may need more FC, some less. In my pool, I can run alot less if I want, because, well, we live in a desert. You, from your pictures, live in a jungle (by my standards). So maintaining a higher FC should keep you from having issues when you have 'events', like rain, leaves, etc.

 

[riny]

Thanks, that makes sense. According to the NOAA, we've had about 15 inches of rain here in the last three months, compared to half an inch for you.

 

[mknauss]

compared to half an inch for you.

When it rains here, it might not be across the street. The street has gotten wet here a couple times since the first of the year.

Right now is our monsoon season. There are areas that have had flash flooding, etc. Us, nothing. That is the way it goes in the desert.

 

[Newdude]

Hey Riny !! What kind of pump schedule are you running ? Along with the elevated FC, it’s super important to have a well mixed pool when it pours. Let’s say you had a whopper 6 inch storm. It would only affect your levels in your 60 (ish) inch average depth pool by 10%. But if that water sat there festering for 12 hours there’d be no promises when it did get mixed in. The cold rain water will sit on top for quite some time until it warms up and mixes on its own but how long that takes is anybody’s guess. (No two storms/days being the same).

I had similar open area immediately over the pool but ‘jungle’ as Marty so aptly called it everywhere else. (). With high winds the rain would blast the trees and continue half sideways to the pool, never even touching the ground. There is no telling what kind of crud will get blown into yours off all that foliage.

So what do you do about it ? Mix. If you know you have an extended storm coming, set the timer to run for 20 mins every 3 hours or so. If a big storm pops up out of the blue like they do when it’s humid out, make sure to mix as soon as you can and not just let it sit until the next time the pump is scheduled.

 

[Sanford35000]

I can totally relate. Our pool is similarly situated in a “ jungle,” and when we get a heavy downpour there’s a lot of runoff that flows in from the slightly sloped grassy area on one side. This usually happens 2 or 3 times each season. I toss in 3 pounds of cal-hypo (35,000 gallon pool) and let the pump run continuously until it’s clear, which typically takes about 24 hours. The waste from backwashing after one of these events looks like chocolate milk. We’re currently trying to figure out a way to prevent this from happening - deciding between a French drain or a curb to divert the water coming down the slope.

 

[riny]

it’s super important to have a well mixed pool when it pours

Thanks, that's a good point. I seem to have a pretty effective schedule, for non-stormy days. The pump runs at 1725 rpm (about 30 gpm) from 8am-2pm and the SWG runs for those same hours. Then it runs at 1100 rpm (a little under 20 gpm) for the rest of the time, 24/7. This keeps the surface completely clean and it's basically zero maintenance. I guess I've been lucky up until now that any storm runoff is heavy enough to sink to the bottom, where the robot can scoop it up easily. We've had a few bad storms this summer and one other overflow, but it didn't affect the water like this.

One key difference I think: the power went out briefly during this storm, and after it came back on, I didn't check to see that the pump came back on. It should have resumed its normal schedule but I didn't check until the following morning. If it didn't resume the scheduled program for whatever reason, that definitely could have had an impact. Also for the future, maybe I'll bump the speed up proactively if I know there's a storm coming.

I'm running now at 2100 rpm (a little over 40 gpm) which was the speed I used for my initial post-construction cleanout. I've been down this road before, so I'll just keep slamming, brushing, vacuuming, and pumping until it's back to normal!

 

[riny]

PS: this was a fun storm a couple of weeks ago:

71888-Video-1

Watch "71888-Video-1" on Streamable.

streamable.com

but the water stayed clear. We didn't lose power that time though which means the pump never stopped. That could definitely have been the difference here.

 

[Newdude]

24/7

I am a HUGE fan. Well done. Disregard the mixing advice but keep in mind if you ever reduce the runtime. (I wouldn’t. Ever. Lol).

One key difference I think: the power went out briefly during this storm, and after it came back on, I didn't check to see that the pump came back on. It should have resumed its normal schedule but I didn't check until the following morning.

8.5 years and I never saw a storm issue. Enough FC and mixing is all I ever did. Most of my friends did neither and saw problems most storms.

Also for the future, maybe I'll bump the speed up proactively if I know there's a storm coming.

Mine was 1200 RPMS for years and then one day I bumped it to 1550 for no reason and left it there. Any speed gets the water moving and does the trick. Now, if you were only doing it for, let’s say, 5 minutes, then sure, get the most volume through the pump as possible.