Help pool algae I think

[Keels]

I have a intex blow up spa and it has worked fine for 6 months, a weeks ago I opened the lid and there was white and black bits on the bottom of the pool looks like algae, I emptied pool cleaned and added chemicals, once heated it appeared again, noticed after cleaning again it was blowing out of filter hole C, emptied again, cleaned again including taking lid apart and washed pipes in control centre brought new filter and again today the bits appeared,

Photos attached

Any ideas I would be really grateful

 

[YippeeSkippy]

Is this something you can pick up easily and smoosh between your fingers?? Is it soft and icky or firm?

What are your test results, and what chemicals did you use to clean and put in the water on refill?

Could this be debris from something else that got into your system?

Maddie

 

[Keels]

It desintergates if you rub it. Some looks like algae others black bits

Chlorine granules and PH plus for our water and occasionally foam remover

 

[Oly]

A spa system is under a lot of biological pressure and keeping it properly sanitized requires understanding, frequent testing and diligence. It is important to purge your spa and plumbing with a quality surfactant prior to emptying and cleaning your spa. Biofilms develop inside your system as a method to protect contaminants from sanitizers. It sounds like you have biological contaminants in your plumbing system that are breaking free into your tub. You may not be sanitizing properly, cleaning your filters reqularly, draining and purging often enough.