Is this algae?

[SteveSwims]

Hi all

Now on day 4 of a SLAM due to OCLT results of over 1ppm (initially overnight loss was around 7ppm but now around 3 / 4.5pom).

Actually started the SLAM on Mon & Tue last week but then ran out of liquid chlorine and had to wait a couple of days for more to be delivered (in the U.K. it’s not so easy to get hold of in a hurry!) so I’m officially counting Friday as the start of the SLAM.

CC is generally 0 / 0.5ppm and water appears crystal clear, so OCLT is the only thing letting it down.

However, I’ve noticed a black line keeps forming in the same spot inside my Aquagenie Skimmer (which was already pretty dirty and I’m trying to scrub it down).

It’s maybe 2inches or so in length and pretty thin. It smears and wipes away really easily but usually is back again several hours later.

Not sure if this is algae or just some other dirt which collected in that spot after scrubbing (as mentioned I’m scrubbing inside the skimmer fairly frequently at the moment to try and clean it up, I don't think the previous owner had ever cleaned it).

I do also get what feels like quite a large number of bugs in the pool (flys, spiders etc…). Of those that I don’t get with the net, some sink to the bottom but a lot of them are collected in the skimmer. Of those that end up in the skimmer, a lot are caught in the basket but a lot also float around the surface, so not sure if that’s a possible cause of the line too?

 

[TinFoilHat]

The SLAM process works very well if you follow it religiously. You need a good supply of LC on hand and then you add it to match your CYA reading for your SLAM level. You have to watch the FC level every two hours or so and keep it up to the slam level until you can pass the three criteria that can end the process. While the chlorine level is at SLAM level then brush the black algae to remove it or at least break the top biofilm layer of it. Brush the pool periodically throughout the SLAM and keep your filter running. Backwash it or clean the cartridges when you see the pressure rise 25% from when it's clean. This can happen pretty quickly during a SLAM.

 

[SteveSwims]

Hey, thanks but all of that is already clear.

I’m just curious to know if the black line n my skimmer looks like algae?

From what I read in pool school, black algae is mostly only going to grow on plaster surfaces, however this is in my plastic skimmer.

So not sure if this is algae or just a point where dirt that I’m scrubbing off the skimmer is collecting.

 

[SteveSwims]

I’m reading a lot about black scum lines at the water line inside skimmers is fairly common.

Hoping that’s what mine is!

 

[ajw22]

I’m reading a lot about black scum lines at the water line inside skimmers is fairly common.

Hoping that’s what mine is!

That is all it is. Scum and dirt in the skimmer.

 

[SteveSwims]

That is all it is. Scum and dirt in the skimmer.

That’s what I hoped, thanks!

Next question is would a scum line contribute to FC loss? I assume all of the bugs that end up in my skimmer also contribute to FC loss too?

 

[ajw22]

Next question is would a scum line contribute to FC loss? I assume all of the bugs that end up in my skimmer also contribute to FC loss too?

There is normal sanitation that is always going on in an outdoor pool.

There is normal FC loss as part of normal sanitation and abnormal FC loss.

 

[SteveSwims]

Got it, thanks.

So during a SLAM, scum lines in the skimmer are definitely just something I want to keep on top of wiping off as often as I can, as opposed to it being the main cause of my high FC loss

 

[ajw22]

So during a SLAM, scum lines in the skimmer are definitely just something I want to keep on top of wiping off as often as I can, as opposed to it being the main cause of my high FC loss

Yup, cleaning the insides of your skimmer should be part of normal maintenance.

 

[SteveSwims]

Just to update, I realised that the weir door in my aqua genie was stuck fully open (laying flat) so the water in my skimmer was only moving very gently (still a new pool owner here so learning about all this stuff).

I tried moving it up and down a bit to free it up but it seems it’s too wide for the opening (if I lift it to the point where it has any free movement then its almost closed and the skimmer starts to empty out).

I have now raised it so it’s just under the water level (stuck in place for now as it’s below the point where it has free movement) and the flow into the skimmer seems much higher (the water is swirling around much more) and since then the scum line hasn’t reappeared (although my overnight FC loss is still too high so the SLAM continues!)

Now to try and find a replacement weir door!

Thanks all

 

[ajw22]

Have you tried trimming the sides of your weir door where it is sticking?

 

[SteveSwims]

Not yet, I’ve not attempted to remove it yet, guess that’s the first thing!