Naitrate spikes ! looking for solution

Hello everyone.

My tank details is following :-

Size 130G
Age 4 Months
skimmer (Aquamedic 1000)
fish 2 tangs
corals around 5 rocks full of mashrooms , 3 open brain , pink carnation coral ( not doing very well is it bending down to the sand all time)
use to have 4 dr shrimps , 3 totally disapeared and the last seen dead after couple days , didn't know if there is something like crap eating them or my damn pink lobster i found dead the other day.
all that happened before the last check on nitrate which hit around 40 min. almost red in the tube . i did 2 water changes in the past 5 days , almost 20% each time. and the % is still almost the same , am planing to do another water change today , same amount as this is the only solution everyone recommended me to do . i also bought 3 bags of de-nitrate and placed them on the sump as my friend recommended me to do.

The question is , when i should notice some changed in nitrate level ?? the other numbers are normal , PH 8.00 , Nitrite 0 Amonia 0. slanity 1.22.

 

What is your water source?

 

tab water , well it suppose to be better here in Dubai than USA , but sure not very clear as RODI , sure am thinking to get it soon

 

have you tested the tap water for nitrates?

 

here is the water test result , this time from the LF store near by .
salt 1.22
NH4 0
NO2 0.1
NO3 40
KH 8
PH 7.8

and he said everything is normal for him !!! maybe "alittle" spike on NO3 but it's not a reason for shrimps to be dead !!! and i just need to rise the PH and salt !!!

i don't wanna comment and i will leave it to you please !!??

 

Tap water have a lot of dangerous chemicals for tank inhabitants, for example chlorine.

Do you have any stores around that sell distilled water?

 

i wish

 

Did you move anything in the tank, disturb the sand at all? Sometimes that can set off a mini-cycle.

 

nope !!

 

if i want to raise pH by adding bicarbonate of soda (baking soda), how much do i need to add on the tank ??? is this safe 100% ? for fish and reef ?? is it recomended.