Cannot get rid of brown algae

My tank started at January 27.
(125x50x50) cm. pure water volume – aprox 250l
No fish – only 10 amano shrimps
Т-24-25 deg

First 15 days lighting was – only 130 w by simple daylight lamp. After some time since start I receive a lot of brown algae, they cover substrate with thick layer.
After that I made my DIY pendant and now I have 2x150 wt MH sylavnia aquaarc 10000K(9000lm)+2x36 T8 lamp, - so in total – more then 1 wt/l.
Lighting schedule is following:
14-00 – 15-00 – 2x36 T8 Osram 765
15-00- 20-00 - 2x36 T8+2 MHx150
20-00 – 21-00 - 2x36 T8

Also after 1 month I start dosing fertilizers. (DIY too)
Dayly dosage :
NO3 – 1ppm, PO4 – 0.06ppm, - K – 1 ppm,
Fe – 0.1 ppm
Mn 0,003
B 0,018
Cu 0,0014
Zn 0,006
Mo 0,0007
Water changes – every week 50% with double dosing after.
CO-2 through ceramic glass diffuser 2.2 bps 12 hours - off for night
Perling is good after 2-3 ours of light on
PH morning - aprox 7.0
Plant grows is not so good (by my opinion – I think may be because of insuff level of K)

BUT I cannot get rid of this brown algae – even it appear that fills very good under such lighting and even grows…

I really tired to collect it form plants every day and siphon its form substrate every water change….

So here I seating and thinking what I do wrong:
1. May be its because My lighting period is not long enough? – but I scare I I add more then 5 hours of MH lighting - I will get thread algae (I even see it now but in really small amount and trying to remove as far as see it)
2. My be because of lonf stem plants on the background (geterantera zosterofolia and hygrofila polysperma) planted very densely and its insufficient light in the lower area? – but on the foreground – its no any density – but the same problems – even more amount.
3.May be something wrong with filtering – cause a lot of algae get to filter (Atman 1200 l/h), when I trying to remove it.
4. I don’t think it because of fert, cause the amount of algae before and after fertilizing not changed.
5. CO2 is in good (not perfect) but good amount
6. Maybe because of my water GH – 15 dGh

Please help me to find reason.
P>S Amano shrimps did not eat this algae at all.

 

2 VaughnH
Thanks for the quick reply.

Actually right in foreground zone- the plant density is low - its only Ehinodorus tennelis several bushes and some crypts -also low amount of Eleoharis.
Two main places where algae appear is:
1. In the background between longstems plant stems (a lot of)
2. in the foreground , right in substrate between and above the small plants.

About CO2 diffusion.
Actually before I have DIY flow reactor (installed after the filter outlet), but then I tried ceramic diffuser cause see that a lot of people use it. Also I have the DIY DC but it works very strange I made it from small penicillin flacon http://www.imbt-vector.ru/img/prof.jpg
And install inside cuted 5ml syringe. Inside DKH4 water+bromotimol blue – and its after some time becoming green-yellow – but its take long time and, for example when I pull t out form tank – its not getting blue only more green after for example one or two hours. I do not know exact reason of it – so I can not measure CO2 level precisely.

About ferts – may be to try 1?5 dayly dose each day – instead of my dosage, … but what the real reason of brown algae – low amount of light, or something else ?

Ohh. My head go nuts about this. ^-)