Water quality, high Nitrate

[Christellearth]

Hi everyone,

First, this is my tank:
55 litres planted tank since 2/12/13
5 neon tetras, 3 shrimps and several snails (who came with the fish ) since 31/12/13
Light is on 9 hours/day.
The filter also produces bubbles.
CO2 system in place.
No algae.

Second, water change:
My last water change was yesterday, 10 litres of tap water, filtered with a Brita filter jug system. I did a proper cleaning of the gravel and added to the new water 2.5ml nutrafin water conditioner, 1.2ml nutrafin plant grow and 2.5ml Tetra NitrateMinus. I measured NO3 and found it still high so I added an extra 5ml of Tetra NitraMinus to the tank.

Third, this is my tap water today:
pH: 7.5
NH3: 0
NO2: 0.1
NO3: 20 to 50 (it is difficult to read
I checked my water provider's website and their NO3 measurement is 37.5mg/l

Fourth, today's readings of my tank water:
pH: 7.5
NH3: 0.6
NO2: 0
NO3: 20 to 50
GH:220 ppm or 12.32 dH
KH: 150 ppm

Question:
I would like to add more fish but I don't feel I should do it until I have the nitrate level under control. Do you have any (uncomplicated) solution to suggest, please?

 

[dmolavi]

You could go with RO/DI water, but you will need to remineralize it for freshwater use.

Alternatively, Seachem Matrix works will (drop it in your filter box), or Seachem Purigen.