This is part of a series on Aquaponic Water Testing.

Silica can strengthen cell walls,help regulate uptake of toxic elements, increase heat tolerance, and slow transpiration. That leads to more upright plants with increased disease and insect resistance. Silica is not necessary for all plants, but may be beneficial to some species. Research has shown that Tomato plants require between 5 – 20 ppm silica for normal growth (link).

In an aquaponic system, I like to aim for a level of 30ppm SiO2.

Testing for Silica

The first two entries are both “Aquarium level” test kits. Use them with caution. I have and use the Hanna Checker HI770.

If you use Fe-EDDHA or Fe-HBED, you will experience interference.

1. Seachem Multitest Silicate (0-25)
   $19.08@Amazon / 75 = $0.25ea
   
2. Salifert Silicate Profi-test (0-30)
   $21.99 / 60 = $0.37ea
   
3. Hanna Checker HI770 (0-200; Resolution 1ppm)
   $51.05@Amazon meter + 6 tests.
   Reagents $34@Amazon / 25 = $1.36ea
   
4. LaMotte 4463-01 (5, 10, 20, 30, 40, 60, 80, 100)
   $70.16 / 50 = $1.40ea
5. LaMotte Smart3 + 3687-SC(0.0-75.0)
   $40.66@GlobalWater / 50 = $0.81ea
    +
6. Hach DR900 + 8185 (1 – 75)
   $72.95@Hach / 100 = $0.73
   +
7. YSI 9500 + Silica HR (0-150; MDL 0.5)
   $56.55 / 50 = $1.13 OR $139.20 / 250 = $0.56

Know of another way of testing for Silica in Aquaponics? Let me know via the comments and I’ll update this page.