Well for a start your going to need a few things
Do i need to buy everything new for my marine aquarium. Not really no, Just make sure no medical treats have been used with any2nd hand equipment.
1: Aquarium / Tank
There isn’t really an upper or lower limit for tank size, but if your wanting to keep fish i wouldn’t go any lower than say 50 litres. AS once you place your rock in then your already losing water capacity of the tank.
If you have a really cheap tank th that looks old then it may be wise investing in a new aquarium as this will be the base for your new marine aquarium and the last thing you’ll want is a leak the next morning.
2nd hand Aquarium’s can be picked up very cheap on the likes of eBay and marine aquarium forums like Ultimatereef.net, having a £200 budget for a tank alone could easily see you walk away with a 400 litre Jewel aquarium Rio with some equipment, or a Nano like mine a D-D 24G.
I bought my first tank new but i wouldn’t, do so again unless i was getting a larger marine aquarium with a sump and all the pipe work. as 2nd hand equipment can be picked up for bargain prices.
Also When your getting your tank you need to think about what fish your wanting. If you just want 2 Common Clown Fish then a Nano Tank around 90 Litres would be fine, but if you want a Regal Tang then you’ll probably want a larger tank around 400 Litres.
Heaters come in varying rating from 25Watts to 300Watts, this is also the amount of Electricity that they use per hour that they are switched on.
I have a 150Watt in my D-D24G nano. Compared to my Rio 180 litre which used a 200Watt. Really the heater size is down to you but the higher the rating of heater the longer it will be.
If you have a large Marine Aquarium then you might want to think of having 1 / 2 heaters.
You can get cheaper heaters from ebay, but should it fail then your water will go could within a few hours and your live stock could then become compromised. so buying a known brand will be best InterPet or Ehiem.
If your buying a new Marine Aquarium setup then it will probably come with a heater so don’t worry to much.
Any Marine specialist will be able to help you get the right heater for your 2nd hand Aquarium.
3: Power Heads
You need to get power heads to move the water around the tank around 40x of your tanks total litre-age is the recommended turn over, so of course power heads are rated in LPH (Litres Per Hour).
Power heads or wave makers can be bought fairly cheap again from Ebay, but you pay for what you get, buy cheap buy twice. I have only ever had New Wave power heads, but you will also see that Koralia Power heads are well known throughout the marine world.
Since your live rock will do the majority of your natural filtering for chemicals. Most new aquariums will come with a filter, there’s no harm in using it. You can run stuff like rowaphos which helps remove Phosphates, in there and other things like Activated Carbon.
You can get external filters for your marine aquarium, which will of course have more space inside them compared to internal filters. But then you have water running outside of your aquarium, which some people don’t like.
New tanks will come with lighting make sure that its ok for marine use, If your getting a second hand tank then you might be able to buy the lighting aswell..
Most commonly seen are T5 lighting tubes. which work fine. but there’s also metal halide, which do cost more to run and buy but they will give better end results.
With the obvious Live rock and Substrate missing you could pretty much get up and running from here.
I’ve used the Cheap TMC Gravel that can be bought in pets at home for around £5 for a 5KG bag.
Rinse the gravel through with tap water first to get all the crap out and then rinse through a few times with RO water this will stop your tank instantly going cloudy when you add the sand.
7. Protein Skimmer
Not a necessity but they do help your tank especially if your heavily stocked. Ican’t explain how they work but its something to do with protein in the water which gets separated in the skimmer and ends up a manky brown colour and thew end produce is skim mate.
You can get the of places like eBay alot cheaper 2nd hand over buying new.
8. Live Rock
You can buy this from your local shop but expect to pay around £10 – £13 per KG. People say you need around 1KG per gallon of water. So 500 litres is around 109 Gallons so that around 100 KG of live, so shop prices you could easily be looking at over £100 in rock.
Second hand rock can be picked up for around £5 per KG but you’ll often find buying in bulk from people closing tanks down is cheaper.
This is only rough so you might get away with slightly less or you might need slightly more.
What do i think
If your tank is going to be the centre peice in your house by new or get a custom tank and then go for second hand gear to recoup some of the costs.
I think i’ve covered everything here but theres loads of other things that you can buy like UV Lights for water treatment and reactors to make sundries last longer.