Brown/Tan Looking Stuff in Bottom of Pool

[ac130loadmaster]

I have done everything possible to get rid of this stuff, that I know of anyway. Since following all the suggestions and using the BBB method I could not be happier with the results of my pool. It is very clear and shiny like I have never seen. I have used pantyhose in my skimmer baskets and have vacuumed to waste several times. Pool has been at shock level off and on for the past couple weeks to help kill everything. But after a couple hours or so after brushing and vacuuming this tan/brown stuff falls back into the same darn place in the pool everytime. I have to be careful when I vacuum because if I go to fast it just clouds up. It's only in a couple places in the pool.

My numbers are as follows:

TC 5
FC 5
CC 0
pH 7.4
TA 95
CYA (Not sure-One pool store says 8, the other says 78) So I just assume its at 78 for now.
Iron, Copper, Manganese (They say 0)
CH 220
Temp 80

Could this be Mustard Algae since it keeps coming back in the same place? I know it's not dirt because it turns cloudy when touched.

Sorry for the long post.

Thanks

 

[ac130loadmaster]

And Borates are at 50.

 

[frustratedpoolmom]

Its probably just dust/dirt/pollen. It probably comes back to the same place because there are depressions of some sort where it's easy for it to settle.

You can do an overnight test to confirm if you have organics. If the FC holds its probably not algae. Many, many folks confuse pollen/dirt/dust with Mustard Algae. Mustard algae grows on the walls, often on the shady side of the pool - and it will dissappear at shock levels, then can return as the FC drops to "normal". If you shock and see this stuff still it's prob not true MA.

 

[zea3]

It could be small depressions in the surface where dirt collects. Mustard algae tends to grow in shady areas and along the sides. If you CYA is 78 then your FC is way too low. If your CYA is 8 then the FC will not hold. You may be keeping just enough FC to hold off a full algae bloom. I suspect the CYA is neither. You need a good test kit so you can check the chemicals yourself. Pool stores frequently use test strips or computer analysis to test CYA and those results are often inaccurate.

According to the Pool Calculator, if your CYA is 78 your daily FC should be between 6 and 11 and you want to keep it on the high end as much as possible. You should never let the FC drop below 6. Your shock level is 21.

 

[ac130loadmaster]

It is definitely in the depressions near the shallow end. I retested my chlorine and FC is at 10. I will shock tonight and see if it goes away, but I do think last time I shocked stayed and didn't go away. I'll try again and see what happens. I am getting a good test kit from here the first of the month. I know I need it bad. The cheaper test kits and pool store testing are not very consistent nor do they seem very accurate. Till I can confirm what my CYA level is, will it hurt to keep my FC on the high side to be safe? Pool looks very clear and I have no smell of chlorine at all and the water doesn't burn the eyes. So I figure the balance is ok. I hope. Thanks for all the input

 

[zea3]

My situation is a little different with an AG pool, but the floor is very uneven and any dust, dirt, pollen, ect that blows in settles in the depressions when the pump is turned off. Keeping your FC around 10 until you get a good test kit should be fine.