All TETRA MARINE TEST KITS TETRA MARINE TEST KITS Tetra Ammonia Test Strips (25 strips)£9.56 Tetra Comfort-Hydrometer T722£15.82 Tetra KH Test Kit£6.34 Tetra Test 6 in 1 Test Strips£9.56 Tetra Test NH3/NH4+ Test Kit£9.56 Tetra Test Nitrate Test Kit NO3-£10.84 Tetra Test Nitrite Test Kit NO2-£7.46 Tetra WaterTest Set£23.70