20000k 150 watt + some corals etc

As you may have read it is important to replace your Metal Halide(MH) bulbs every 12 - 18 months as the wavelengths of light (colour) tend to shift therefore, not giving your corals etc etc the best spectrum possible. When I first started this blog I added a 150 watt MH with I believe a 13000K bulb. I purchased the tank + accessories of eBay so wasn't 100% sure how long it had been since the bulb had been changed so decided to purchase a new bulb.

There are a number of different types of MH bulbs available i.e. in terms of Kelvins. The standards ones you are able to find in OZ include:

- 6000K (High-end planted tanks - gives your aquarium a very yellow looking light)
- 13000K (Marine aquarium - with some corals however, lacks blue wavelengths therefore, corals won't look as nice - probably not the best for Small Polyp Stony {SPS} corals - white looking light )
- 16000K (a mix between the white and blue spectrum provided between 13000K and 20000K - would work well for reef or coral free aquariums - crisp white light)
- 20000K (This brings out the best colouring in your corals + gives your water a colour similar to deep ocean .... blueish lighting)

Everyone is different and prefers different lighting for their aquariums but, I would suggest you go for the crisp white light as a minimum for your tank if using MH's.
Another reason that I did change my lighting to 20000K bulb was because, I noticed that my SPS corals weren't doing as well with the old 13000K bulb. I recently bought a Acropora and after putting it in my tank it appeared to go a tinge of brown (Itc ould just be due to a conditioning period....). I have read and, I don't know how plausible this but, when the wavelength of light drops off the Zooxanthellae in the corals move forward i.e. into the top layer of the coral and therefore the coral loses its colour and, goes a brown colour due to zooxanthalae being brown (Not sure this has been proven either way). I can say however, that after changing the bulb the Acropora and Montipora's colouring improved.

So have attached a couple of pictures so you can compare:

Nice Flouro Orange Fungi

Bi-Colour Hammer Coral (LPS)

2 x Monti Plates
Acropora (was a dark brown when I fist put it in the tank but, now is starting to colour back up)