fresh to salt conversion?

[elusive_fish]

Even though my malawi tank is healthy, attractive and breeding like rabbits I still have this crazy desire I can't shake to change it to a marine tank... if I can do it at a reasonable price.

After some digging around here is my idea:

A lightly stocked FOWLR tank (5 or so fish)

That way selling my current fish would probably pay for the rock (but i'd still have to buy the fish, obviously). I could keep my aragonite sand, current lighting and probably still just run my cannister filter. I'd imagine i'd also have to get something to create current?

My hope is that if i am keeping it lightly stocked i won't have to worry about sumps/protein skimmers etc for the mean time. I could add a sump/refugium/better lighting/protein skimmer etc if i really enjoy the marine fish and have the money required.

Does this seem reasonable/feasible?

[spoon]

sound good to me but perhaps check with someone if using the sand that has been in freshwater is alrite? i know coral rock absorbs nutrients in freshwater i dont know if sand is the same.

and if you plan to use your cannister filter remove all the media first and use it for flow or to add carbon or purigen etc . let the live rock be your biological media. i would also leave the sand out for the time being until the tank is better established as its annoying to clean and will quickly get covered in algae and diatoms

[carznkats]

I think that should be fine. At least you can source fresh saltwater easily to enable you to do weekly water changes as this will help to keep the nitrates etc down. If you still want to use your canister filter do what spoon recommended and remove all your media and leaving it mostly empty with some purigen, phosphate remover (helps control algae).

Good luck with your plans

[elusive_fish]

So why are some marine people so anti cannister filters? Apart from the buffering properties of coral rock, how is it really any different from bio noodles? Both are just porous homes for beneficial bacteria, right?

I'll be at the next TT meeting, so hopefully I can say 'hi' and get some more advice from you guys in person too

[suphew]

Bio noodles are very good for hosting aerobic bacteria which results in nitrate. Coral rock is very good at hosting anaerobic bacteria which takes the nitrogen cycle a step further and converts nitrate to nitrogen gas.

Nitrate at reasonable levels isn't a problem for fish even salt water ones but it is deadly for corals and other invertebrates.

[elusive_fish]

Bio noodles are very good for hosting aerobic bacteria which results in nitrate. Coral rock is very good at hosting anaerobic bacteria which takes the nitrogen cycle a step further and converts nitrate to nitrogen gas.

Nitrate at reasonable levels isn't a problem for fish even salt water ones but it is deadly for corals and other invertebrates.

Thanks suphew, that was a good explanation. But if the aerobic bacteria that are found in cannister filters still be breakind down ammonia to nitrites and nitries to nitrates... then the anaerobic stuff finishing the job? Sorry if its a dumb question, this marine stuff is all new to me

[suphew]

The idea is to use a skimmer to remove most of the waste before it breaks down then the live rock removes whats left. If you start using canister filters etc they are designed to collect that waste and break it down (which is what you want in a fresh water tank) and will do this before the skimmer has a chance to do it's job. So in effect your creating Nitrate that you didn't need to have in the system, canister filters are nicknamed nitrate factories because of this

Fresh water filtration systems in general are designed to collect the waste in big chunks and break it down, salt water systems are design to keep the waste in the water column so that the skimmer can process it. One of the reasons that salt water tanks have so much water movement is to keep waste from settling.

HTH

[elusive_fish]

OK Thanks again Suphew, another good explanation.

For someone like me, who will be doing a lightly stocked FOWLR and no protein skimmer to begin with, would I be better to keep the cannister filter going, or just remove it from the system and rely on cycled rock and power heads to move water?

[suphew]

Personally if I was going to use a canister I would use it for running chemical media, carbon, phosphate resin, Zeolight, etc. You can use it like a fresh water tank filter if you are running fish only, but with a low fish load you shouldn't need to and the problem is sooner or later you will add corals, plus you can run a far cleaner, healthier, better looking, tank by doing it the 'proper' way. Skimmers cost no more than good canisters now days, and they often come up second hand, when you factor the cost of losing expensive fish because of poor water quality it makes sense.