Need info about diatoms & Reef tank cycle

[Nagra92]

Hello guys hope you all are doing great ..
Question 1
My aquarium is 7 months old , i have gone throw the green algae bloom now it is gone
But from last 6 months diatoms are not going anywhere
My fish & corals are doing great ..
Question 2
I have no sump and no skimmer in my 55 gallon tank only hang in back poshphate reactor and canister
2 months back i installed one tray on the top of aquriam and with some white cotton the water flow froms it .. but every other day it turns brown due to diatoms i guess i clean them and install them again
But here i am thinking that may be this is the cause of diatoms because my VIPRASPECTRA 150 watt LED is directly focused on my tray which contains cotton ? And may be thats why i am not getting rid of diatoms
Or i dont know if this is Natural phenomena that Diatoms take 7 months to disappear ? Please guide me anybody
@fabutahoun

my aquriam 55 gallon mixed reef tank , 7 months old
Led 9 hours
1 hour all white
7 hours blue + white
1 hour all blue
Whites 20% & blues 45%

 

[mrlogan24]

What is your cleanup crew?

 

[Idoc]

Not quite an emergency, lol.

But, diatoms mainly feed on silicates in the sand and rock. By 7 months, you'd expect them to be gone. If you are using tap water, that could also be a source.

Do you notice those big brown patches on the sand less before lights come on and then worsen with the lights on? It looks very suspicious for dinos.

What are your testing results? Nitrstes looked like zero on your api test. What is your phosphates?