Metal Halides vs CFLs in Aquariums – Installed a Metal Halide Lamp a few weeks back …

Motivated by some ‘knowledgable’  aquarium enthusiasts, I was motivated to improve my aquarium lighting and install a 70W MH lamp. It was DIY setup, the steps for which i will post later. The lamp was a OSRAM HQI-TS NDL 70W, details :-

It was a 4200K lamp, so not ideal, however was told that it would work just fine.

So what do i think of the two philips CFLs (PL-L 36W/865/4P) vs  OSRAM HQI-TS NDL 70W after a couple of weeks of operation, well I think the CFLs win hands down !!! And, what do i base the assessment on, simply on the oxygen bubbles i see forming on leave when i use the CFLs vs the MHs in the same tank….

However the jury is still out on the MH vs CFL debate, since the above is not really a completely fair comparison. Why? Because, the MH is 4200K and the CFL are 6500K, i am still hunting for 6500K MH but no luck so far where i live…

What kind of light is best for a planted aquarium

After fixing the aquarium with two philips CFLs (PL-L 36W/865/4P), doing some more research on what kind of light is best for aquarium plants – i mean not in terms of lux or brightness but in terms of light temperature i.e. cool, red, blue what ?

Based on some initial research on the internet found that : Chlorophyll does not absorb all the wavelengths of visible light equally,  light absorption is maximum at 430 and 662 nm. This means that lights which have peaks in their output color  spectrum around this range are the most efficient for plant growth.

Lets review the light spectrum for lamps that i put in :-

Light spectrum for Pl-L 36W/865/4PColor spectrum


There are two small peaks around 430 and 662 nm but the largest one is around 550 nm which is not going to be that useful. Let me do some more digging around and see what comes up…

Lighting for Planted Aquariums (watts per gallon, LSI, lumen, lux…)

Having setup a planted aquarium and finding that my plants were not doing too well inspite of having 03 CFLs in an 80 liter tank, i realised there must be something fundamentally wrong. Assuming that  the light was sufficient, I set out of check the substrate, fertilizer etc etc. When those did not help either, came back to the fundamental question on light. Wearing out my finger hitting the Google search button on the internet and after reviewing many article on the subject, I thought i would share the result of my research on Aquarium lighting for Planted Aquariums which may benefit others struggling like myself.

Continue reading