I have kept freshwater fish on and off for around 15 years, and have never took up the task with as much interest as I did the day I decided to try my hand at a saltwater aquarium.
The biorb gets a lot of bad press, people hate it due to it's shape and lack of surface area, and for those reasons I was sceptical about trying a marine set up in one, but I believe most of the reputation is down to bad set up and maintenance rather than the tank itself.
Other reviews complain of the cost of the tank, which initially can be expensive, but there are plenty of used ones available, and of course the service kits, which I think are relatively good value, i've yet to find another exotic pet which costs less than £10 a month to feed and maintain.
Many of the stockists I visited told me the tank was inadequate for the marine conversion, and it wouldn't work successfully, but despite this I decided to give it a go, which gives me even more satisfaction.
I own the 60L version, and have all the toys for it, LED light, Iheat etc and love the look of it on my sideboard.
I bought the conversion kit, followed the supplied instructions, and have not had any problems whatsoever despite having no previous marine fishkeeping experience, it was very easy to set up, and has run for 6 months flawlessly.
I put in 3 bags of the media for the biofilter to make sure there is plenty of area for it to multiply, as this is probably the most important part of the filtration.
One bit of advice I would give is to follow the instructions TO THE LETTER, but be careful when it comes to putting fish in, especially if you are stocking Clownfish, as this is better done in pairs, as long as they are small sexless immature fish, not one at a time as per leaflet, otherwise they will both become female and fight continuously until one dies, but please never consider stocking clowns in any tank smaller than the 60L.
I would recommend the purchase of an API saltwater master testing kit, this will enable you to follow the tank cycle, and know when the best time is to begin putting inhabitants in, as stocking before the tank is cycled will result in a major catastrophe, mine took 7 weeks not the suggested 6, without testing the water it would have been easy to stock with fish too early and wipe them all out.
I will point out that stocking clownfish can be stressful, they have a clear pecking order when in the wild, and going through this natural process of fighting for supremacy can be at times brutal to watch, I am a fish lover, but contemplated several times removing them as it was almost too much to bear, but it does take time (and some strategical feeding), and once they click and the female darkens in colour it's bliss I have to say, but there were times I never thought we'd get there.
I have 2 Hermit crabs, and two Percula Clownfish living very happily, it's one of the best talking points in my home when visitors call, especially the crabs.
Do it right, and it will be a pleasure, the key is not to rush it, it will be sat without fish for weeks while it matures, but it's worth it.
UPDATE over 3 years in.
Still experienced no problems after over 3 years, my fish and crabs are thriving and have at least doubled in size, I tested the water and recorded the results every week for the first few months, and now on a monthly basis (2 weeks after each clean out) and the water parameters are rock steady.
I feed with Hikari Marine S pellet and nothing else, my clown's and crabs love them, live food like brine shrimp should never be put in a Biorb aquarium as it's too small in volume to cope with the waste created, and has little nutritional value to your fish.
I've added a Scarlet skunk cleaner shrimp to the clean up crew and it adds another interesting critter to the tank, but he does shed his exo-skelleton every three weeks which is amazingly delicate and makes you think he's multiplied overnight, and the last cleaner added was a serpent starfish who only appears after dark, but keeps the tank as clean as a whistle.
It pays to do a bit of reading about your chosen fish and invertebrates, this helps you to understand the behaviour patterns, and what's safe to mix with what, as some are very territorial and shouldn't be put into a small community. As with all hermits new empty shells are needed to allow growth, so a scattering of spares in the tank will prevent your crabs fighting over one particular one, and it's fun watching them examine and test drive a new home.
I must stress I have done everything as instructed with regards to maintenance, and it has kept everything in check. I also found the egg shaped timer that BiOrb make invaluable, I've popped it on my TV stand beneath the screen, and it flashes to remind to feed, and when tank maintenance is also due, you'd be surprised how easy it is to forget!
I have recently set up a Biorb Life 60L additional tank, better to do this than be tempted to overstock your tank with more critters and fish, this is a stunning piece of kit, and was cycled with substrate and water from my mature BiOrb I have now stocked something different, and have a pair of onyx clownfish with a few red leg hermits to keep them company, along with a blood shrimp which is beautifully coloured.
I use a bucket (15L) with a side mounted powerhead and heater when preparing water for a change, this sees the salt is perfectly mixed and dissolved, and guarantees the the water is up to temperature when changing, avoiding any undue stress to the fish and invertebrates and it seems to work well, and I would recommend this method to all.