Water is clear, CC is 0, but algae is still present?

[asura1]

I think my eyeballing skills are terrible, or the pool capacity is smaller than 14k gal, or both - two hours ago I added what I thought to be enough chlorine to bring FC from 8 to 12, but I just tested and it's sitting at 18

 

[Texas Splash]

I just tested and it's sitting at 18

Not the worst thing to happen. It will fall. It could be either the test itself or the info used in the APP. If it happens again, your pool size may be smaller than you though and you can adjust accordingly.

 

[asura1]

This morning's test shows FC 14.5 and CC 0.

I didn't measure last night because I knew FC was still going to be high and could still see the gunky stuff on the floor, so no chance of passing SLAM.

But I did do a little experiment yesterday, which confirm's Texas' suspicion about the filter - I adjusted the return jet at the shallow end so it would be blowing towards the wall instead of centre of the pool.



and this morning it appears that more gunk appeared along the side of the wall than towards centre of the shallow end.

If this makes sense, then I should seriously think about getting the sand deep cleaned or even replaced (no idea how old it is).

For now, would frequent backwash (after every vacuuming session) make this better?

 

[Texas Splash]

For now, would frequent backwash (after every vacuuming session) make this better?

Perhaps. Or you may need to add a little DE to try and compensate at some point. That is only if the junk you are seeing settle is just non-algae debris.

Add DE to a Sand Filter

A clean pool filter will increase the efficiency of your pool! ... your filter are to backwash it, clean the manifolds and grids, and add new DE.

www.troublefreepool.com

 

[asura1]

I did two cycles of backwash 60s + rinse 20s right after vacuuming. When I turned the filter back on, I saw return jets blowing pale green stuff (dead algae?) back into the pool for about 10 seconds. Something not right for sure.

Honestly I'm starting to feel a bit like Sisyphus

 

[Bperry]

I did two cycles of backwash 60s + rinse 20s right after vacuuming. When I turned the filter back on, I saw return jets blowing pale green stuff (dead algae?) back into the pool for about 10 seconds. Something not right for sure.

Honestly I'm starting to feel a bit like Sisyphus

Try backwashing longer and rinsing longer. It takes a solid 30 to 60 seconds for mine to start spewing out dirty backwash because it takes a minute to clear the lines of the clean water that’s in the plumbing

 

[asura1]

Good morning all, I have passed OCLT (overnight loss is 0.5), CC is 0 and pool water is clear as before, but there is still dead algae? on the floor.

if the pool water doesn't clear up soon from the SLAM, that might be the next step

If this goes on for longer, must I clean the sand first or can I raise the SLAM level to mustard algae anyways?

Another thing I found is the pool lost about 3/8 to 1/2 inch of water overnight. I've been suspecting water level is going down a little too quickly, but haven't been able to do a proper 24h bucket test because of rain. Think I will do an overnight test tonight first.

 

[Texas Splash]

If this goes on for longer, must I clean the sand first or can I raise the SLAM level to mustard algae anyways?

You should not need to increase to Mustard Algae levels. If the stuff you are seeing on the floor is a light grey or white color, it is probably dead algae or other organic material. You can just continue to vacuum that up or sweep towards the skimmer. This may also be a good time to add just a little DE to the sand to help it filter a little better. I think I gave you that link before to add DE.

Let's save the suspected water loss for a different thread later once we know you are 100% in the clear here with the algae.

 

[Texas Splash]

At this point, I would allow the FC to fall back to normal levels (at least below 10) so that you can validate the pH and anything else you need to test. Good job sticking with it and passing the SLAM and OCLT!

 

[asura1]

Thanks Texas for your kind words,

If the stuff you are seeing on the floor is a light grey or white color

the thing is, I'm not confident that the stuff looks how you would describe it, it still looks kinda brownish to me as before

 

[JamesW]

I think that it is probably mustard algae.

 

[Texas Splash]

The one curse about TFP clear water is you see everything down there whereas before you might not have. Now you see all the dirt, dust, and local debris that settles to the floor. That could be what you are seeing. I suspect if that was algae you would not have been able to pass the OCLT.

 

[Texas Splash]

James has a different opinion on that material. To be safe, you could bump the FC up to MA now and just to be safe. Certainly up to you.

 

[JamesW]

Mustard algae can be very slow to react and you can pass the OCLT with mustard algae.

In my opinion, I would go to mustard algae SLAM level.

 

[JamesW]

I just tested and it's sitting at 18

In my opinion, this is the lowest I would go.

I would be a lot more aggressive with the FC level.

If I was doing it, I would probably be in the 20 to 30 ppm range for FC.

I am not recommending this, just telling you what I would probably do.

That might risk some bleaching of the fiberglass color, so you have to decide if it is worth the risk.

 

[JamesW]

If the algae is just shrugging off the FC levels, it is telling you that the FC is not high enough.

You have to keep increasing the FC until the algae is killed.

Mustard algae is very resistant to chlorine and you have to be aggressive to kill it and keep it killed.

Note that there are risks to going above SLAM level and you have to consider the risks vs. the cost of dealing with this for many days trying to eventually break it.

 

[asura1]

In my opinion, this is the lowest I would go.

I would be a lot more aggressive with the FC level.

If I was doing it, I would probably be in the 20 to 30 ppm range for FC.

I am not recommending this, just telling you what I would probably do.

That might risk some bleaching of the fiberglass color, so you have to decide if it is worth the risk.

I can live with it if the risk is cosmetic. To me, the pool is more for swimming in, less for marvelling at.

 

[JamesW]

The fiberglass might get chalky due to oxidation from higher FC ratios.

It is a tradeoff for trying to clear stubborn algae.

 

[asura1]

So I have kept FC at 20-25 for the past day or so (using 5ml for FAS-DPD test to conserve some reagent, so probably not extremely precise), and this morning I'm only seeing some modest improvement, if any.



I have been voraciously reading posts on this forum that could be relevant to my situation. It got me thinking, is there a possibility that this stuff is not algae, but pollen or some other debris?

I put in a skimmer sock yesterday and this is how it looked this morning,



Would algae leave a yellow residue like that?

Another thing is my pool is basically situated in a forest,





Lots of trees and flowers and other plants around it.

Forgot to add that all parts of the pool get some sun each day (half in the morning, half in the afternoon)

Any thoughts? Either way I'm prepared to get to the end of this.

 

[JamesW]

Hard to tell for sure exactly what it is.

I would continue the SLAM.