Algae problem!! or not??

[hungrydave]

Hi Everyone! Hope i will get some help from this Community! sorry for my Englis i'm a Hungarian guy who needs some help!!!My love with fishkeeping was started with a freshwater aquarium and after i turned to saltwater! when i started my saltwater tank i know started the wrong way by using tap water!!!! Results tonnes of ALGAE!
So i did restart the whole tank by removing all the rock brush the algae down i did keep the sand and 50% old water! It was nice for 2-3 weeks and the brown algae are back! im not sure its diatoms and the tank are just recycling?!
but i see some gas bubbles on the rock is well at night time??? Now im using a 4 stage RODI Unit! please help me with some advice what i need to do just leave it or i missed something??!! Thanks for the helps!!!


my tank parameters: 400L Aquarium
Calcium 450ppm
Magnesium 1360ppm
Alkalinity 11.8
PH 8.2
Ammonia 0
Nitrite 0
Nitrate 5ppm using red sea nopoX
Phosphate 0.09
Salinity 1.025

Lighting 2 x 150w AquaMars LED 9-10 hours
Water change every week 15%

 

[Bent]

Tank age
What kind of rock
Is the rock and sand the same rock and sand that were in the tap water?
How long since you started using R/O water.

 

[avery155]

Bubbles could be accumulation of micro bubbles in the water column, do you see any in the water from your return nozzle or powerheads?

 

[hungrydave]

Hi! The tank is 5 years old but i did a complete restart about 4 months ago! using RODI water over 6 months now!
i see no bubbles coming from my return nozzle!!

 

[mcgyvr]

We will need pictures..
You could have dinoflagellates

 

[hungrydave]

Here is some photos! Those rocks were clear 2 weeks ago!

/Users/davidbrlas/Downloads/IMG_0398.JPG
/Users/davidbrlas/Downloads/IMG_0397.JPG
/Users/davidbrlas/Downloads/IMG_0395.JPG

 

[hungrydave]

Here is some photos! Those rocks were clear 2 weeks ago!

 

[hungrydave]

Here is some photos! Those rocks were clear 2 weeks ago!

 

[mcgyvr]

From what I see its likely diatoms and maybe some cyanobacteria..

 

[hungrydave]

any advise how to beat them? doing 10-15% water change dosing NOPo X is good?