Pre filtering for marine reef aquariums

The photo that follows is just a small example of why all marine aquariums need pre filtering, even live rock bio filtration, you need to put an affective barrier of no less than 100 micron of Dacron as it leaves the tank, or a sectioned off part of the aquarium where the water has to go through the Dacron and than back into the tank area, you will not regret it!!

Of course it has to be cleaned two or three times a week or the rubbish captured by the pre filter Dacron, is still in your water, plus if the Dacron isn’t changed or cleaned under water with totally different temp and PH,like tap water, than after 5 to 7 days in your water it will start to house bacteria and protists that can exist in this and become part of your biological filtration.

You move it than and the tanks water will become somewhat un balanced as if you just removed or moved a part of your biological filter media.

This is not a great issue with just corals as a reef tank, corals make very little waste and even than the algae clades with in the cells of the corals utilise this waste converting it via photosyntheses into food for both coral and algae, leaving the tank mostly free of waste particles, but what of the foods you feed the corals and the algae that is scraped off the glass or section that breaks free from some where and invertebrate shells as they are discarded.

There is a lot to be considered when working out, should I pre filter?

Pre filter means to remove waste that will block or pollute bio areas and live rock is a bio area and the porus aspect of it will become blocked as the rubbish is moved around the tank, no matter what!

You combine coraline algae covering the surface of your live rock, the small holes in it (porus) blocking over time from small particles of rubbish, how well do you think it will be bio filtering later on?

That’s one of the reasons live rock bio filtering needs propping up!

If rubbish and detritus is not removed via a barrier, like a net capturing dust and organic particles for your air con, than these trouble some particles will give your tank grief as time goes on.

Don't count on a skimmer to do this work,it will not work any where near good enough!


This is my algae scrubber filer wool barrier after just two days, imagine what that would do over time!

WOW - how many days does it take for your prefilter to look like that ?

It takes just under two days to get like that, this pre filter that is, there are two stages of pre filters,never have any less than two, I replace their Dacron bags,( I make my own), each two days and put them in a pile for the next time we use the washing machine.

I make four sets each time,each four sets last me a few months and they are put through the washing machine regularly,the third set for this tank to be made soon,it takes about $1 in materials and 20 minutes to make four sets.

If I forget to replace them, there is a fail safe over flow that will last for up to two weeks so if we go away or what ever, there are no worries!

Every thing I make has a failsafe,so nothing fails, that is because every thing has had its failures and preventing the failures from reoccurring is the be all of tank longevity!

You see people in the hobby normally give up on it and sell the gear or have to replace stuff constantly or put it in the shed or give it away or buy more tech and get poorer.

This is why the net is a such a money making concern and for some a let down on their hobby interests, especialy a forum with lots of sponsorship directed at one type of hobby, but that’s to much to rave on about now.

You see after the 6 month to two years on average part of the hobby has passed, around this time it all starts not being as good as it was or was hoped for or could have been!

The more relentless problems start from no pre filtering and this is mainly because of the fish (they do most of the more serious polluting in more ways than one) plus coral does not get white spot,lol,and can last for ages before it was doomed to slowly die any way, so a reef tank, not many fish at all, can normally look better and be looking alive longer but is doomed any way.

Lots of waste is made in the ocean mate and this is our try at a captive part of the ocean in our home.

A mate had three skimmers,one worth just over $8,000,all three 4 to 5 feet high and massive,he had so many wipe outs its not funny,also in play was miracle mud,calcium reactor,nitrate reactor,commercial grade UV sterilisers,ozone generators,thats just some of it!


Try years of skimmer use and making your own and also watch the more modern skimmers,needle wheels as such in action by friends and you realise they do not do what you are told they do,to the degree you are told any way,that would take years to show it and most have given up or moved on by than,you see my point!!

You should see the other pre filter as it blocks,yuck,lol,they are a very messy essential thing!!

Yes I hear ya - I have been interested for 30+ years with a renewed interest of late - the come and go always happens with any hobby. My success has been from good luck and regular water changes more than anything and that is what I aim to change. Forums like this and experience like yours is everything. As you say many crashes and mistakes to learn from and it seems your observation and practical experience is paying off for you now, through my questioning and your generous answers I aim to get up to speed - with a dream of breeding on a large scale along with Coral cultivation to offer my small bit of conservation; I'm driven by the challenge which is # 1. Getting the fundamentals correct is key and I feel this is something you do well!



Keep it going - lots more questions coming.....