Filtration for 300 Gallon Fish Only Tank with no Live Rock

[apache2a]

I have some experience with both fish and reef tanks in the United States. I now live in the Philippines and would like to have a tank. I would really like to have a reef tank, but all coral, live sand and live rock is illegal to possess (crazy I know). My idea of course was to have live rock as my main filtration media, but since it is illegal to possess it, I have to turn to alternatives. I won't have coral, just fish and possibly inverts and anemones which are OK, but right now mostly just looking to have fish.

Without live rock, how would you set up filtration?

I have a 100 gallon acrylic tank (kind of scratched up) I plan to use as a sump/refugium. I was thinking of using bioballs...but looking through threads the majority seems to think they are nitrate factories. I will run a skimmer.

I was thinking to get a couple thousand bio balls and have that set up from the overflow (using a sock filter before it). One major question, if I have bioballs in the sump where they are not getting the trickle/flow from overhead, can they act as live rock in taking out some of the nitrates?

Then in the second larger compartment of the sump, the tentative plan is to make it the refugium area mostly just with algae under grow lights.

Then in the last smallest part having the skimmer, before the return to the tank.

I thought about putting bioballs after the skimmer...to skim before it goes for the bio balls to work, but not sure if that would help any.

Any additional ideas are greatly appreciated.

 

[Michael Hoaster]

Welcome to RC apache2a!

That's a pretty unique situation you're in. First off, bio balls or any other bio media will work fine in a fish only tank. Yes, they do put out Nitrate, but the fish are fine with it. This could give you algae issues though.

Another option is a deep sand bed. These can support a diversity of nitrifying bacteria and denitrifying bacteria, which takes care of the Nitrate. Using your sand bed as a filter suggests it can be optimized for the purpose. I'd recommend a layered approach to increase bacterial diversity. Start with a layer of very fine sand on the bottom. This is where the majority of the denitrifying bacteria will colonize, because of anoxic conditions (no oxygen). Then add a layer of medium sand for anaerobic conditions (low oxygen). Top that off with a layer of very course gravel for the high oxygen conditions that nitrifying bacteria like.

Also consider marine plants like seagrass and macro algae. These will provide some much needed structure for the fish to feel safe, as well as excellent filtration that also oxygenates the water.

Providing hidey holes for all your fish is going to be challenging without rocks. You'll need to be creative. There are fake rock recipes floating around the web you might look into. I built a fake back wall on my 180 for a harem of Royal Grammas, that I built lots of caves in for them. I used the pond version of expanding foam to build it.

Well that's some thoughts. I hope its helpful. Good luck!

 

[apache2a]

Follow up questions.

Follow up questions.

Thanks so much, I really appreciate it.

2 follow up questions. 1. I think regular sand (non coral) is called aragonite sand? As ridiculous as it seems to me, live sand it illegal, but I would be ok with aragonite sand. Can I do the same thing with this type sand and gravel that you were talking about?

2. I thought about making my own live rock (and they sell artificially made live rock as well). From what I've seen it is made of aragonite sand/gravel and cement....honestly I have some reservations about putting cement in my tank. Anyone have experience with home made live rock? Does it function the same basic way as regular live rock?

Thank you very much.

Honestly, most people here just have reef tanks with corals and live rock anyway as the authorities don't really care as long as you aren't selling them (and people regularly buy and sell them to one another personally, just not in stores) but I really don't want to have it hanging over me that I could potentially have problems. I'd rather just do it legally, still have a beautiful tank and have peace of mind.

 

[Michael Hoaster]

Here in the states, non coral sand is usually silica sand. Aragonite sand is coral sand, and likely more available where you are, but not necessarily live. Bottom line is yes, aragonite sand is ideal, but really any sand will do. It's not even necessary to use different grain sizes to get nitrifying and denitrifying bacteria. You can get those zones in a single layer of fine sand. My suggestion of the three layers is a way to increase bacterial capacity for increased filtration capacity.

I've looked at garf.org for their "aragocrete" rocks, but I have no experience myself. I would think you could find someone's experience with it online. It functions like live rock in that it provides surface area for bacterial colonization. The big difference is that it has no life on it, like algae, sponges or worms. So any non-live, or dry rock is kind of a blank canvas. If you want that canvas to get covered in 'good' bacteria, leave the lights off for the first month or two, until the tank has cycled. This will help you avoid algae. Also you may need to cure or soak the rocks in water for a month or two, to avoid it leaching anything into your tank.

Good for you, doing it legally! You'll show 'em it can be done.

 

[apache2a]

Thanks again. I think I'll probably go with making it myself. I might even put it on the reef for a week or so after I cure it to let it get live....all I have to do is put it there, so thinking I might as well.

I'm not quite sure what to do about the sand...live sand is supposed to be illegal, but if I got aragonite it would become live anyway. Haha...so I'm not quite sure what to do with that.

Any way I slice it, it should be fun though. The fish are way cheaper here too, in Manila, and there is a local boat that is usually around that collect fish and I might be able to get them even cheaper...which would mean no transport either...just from the reef to his holding tank for a few minutes then 15 minutes back to my house. I was a little disappointed at first with the regulations, but I think it will be really fun.

 

[Michael Hoaster]

Jealous! Have fun with it. You are living an aquarist's dream!