Refugium substrate: to sand or not to sand?

[KeTos]

I'm in the process of redesigning my sump, going skimmerless and enlarging my refugium.

 

I've been debating what to put in the fuge. I'll be growing cheato in there. "Miracle mud" is out of the question because it's so expensive, but what about sand? Or should I go bare bottom? I know there are a lot of differing opinions on this matter, but anyone have experience, insights or regrets with refugium substrates?

 

The tank is a Mr. Aqua 17.1 gallon with a standard 10 gallon tank as a sump.

 

 

[billygoat]

Sand in the 'fuge would certainly bolster your biological filter, but unless you are planning to grow some sort of algae that specifically requires a substrate (e.g. Caulerpa prolifera or the like) it's probably not strictly necessary. If it were me, I'd probably add sand just for the heck of it. Chaeto definitely doesn't need sand to thrive, though.

 

Is the 'fuge going to be visible? If so I would add sand for sure.

[KeTos]

Won't be a display refugium, although I agree that sand just looks a lot nicer. I'll probably just stick with cheato for now to simplify things - main reason for enlarging the fuge and going skimmerless is to have one less thing to maintain as I have two small kids in my home. 

 

I know this has been hashed out before here and on other forums, I've just never seen it come to a clear consensus, probably because there are multiple ways of doing things that all work in the end. Some people swear that sand is a detritus trap, others swear that it's a source of biological filtration. Thanks for the input, and congrats on an awesome TOTM!

[billygoat]

1 hour ago, KeTos said:

Won't be a display refugium, although I agree that sand just looks a lot nicer. I'll probably just stick with cheato for now to simplify things - main reason for enlarging the fuge and going skimmerless is to have one less thing to maintain as I have two small kids in my home. 

 

I know this has been hashed out before here and on other forums, I've just never seen it come to a clear consensus, probably because there are multiple ways of doing things that all work in the end. Some people swear that sand is a detritus trap, others swear that it's a source of biological filtration. Thanks for the input, and congrats on an awesome TOTM!

Makes sense to me! I think there are easier ways to bolster your biological filter if you feel the need for it down the line; for example you could simply add some Matrix media or one of those big porous bio-bricks and just plop it down in the 'fuge under the chaeto. That would be a lot simpler and less messy than adding sand... though admittedly it would not provide a substrate for pods and other beneficial benthic micro-fauna. 

 

The debate over sandbeds is definitely an ongoing one, but my personal experience suggests that a sandbed is beneficial so long as it is populated with a healthy variety of tiny benthic animals and microorganisms. I have not done anything to my sandbed over the past 15 months of running my tank, and it has not been stirred or disturbed in any way other than through the activities of burrowing animals. Seems to be working out so far, though I admit that there's still a chance that it proves to be a slow-ticking nutrient time bomb... but we'll cross that bridge if/when we get to it. 😅

 

Also thanks for the compliment! I'm glad other people are enjoying my tank as much as I do. 😊

[RedCrow]

I’d go with a couple inches of rubble. Lots of room for pods to grow and multiply there, plus it’ll ad to your bio filter 

[mcarroll]

On 3/4/2020 at 1:44 PM, KeTos said:

I've been debating what to put in the fuge.

What's the problem you're trying to solve with all these changes?

 

Are you sure a refugium is really the answer?

 

Growing macro algae will only work (or be helpful) in a tank that has persistently high nutrient levels.

 

Excessive bio-media (mud, sand, rocks, frag rock, bio-bricks, et al.) can cause nitrate depletion in an otherwise well-run tank....it also needs persistently high nutrient levels.

 

Unless there's something weird about the display tank, the live rock in your display should be a more than adequate bio-filter.

 

Consider that a protein skimmer is part aeration device, part mechanical filter....arguably more aeration device...it's not that great at removing particulates or dissolved materials.  (We like that.  Over-filtering a reef is bad.)  

 

The beauty of a skimmer is having that combination of features in a package that requires very little to keep running...just clean it every so often. 

 

Nothing but skimmate goes in the trash.  Nothing needs to be routinely replaced.  Very little power is consumed.  And its action is roughly analogous, ecologically speaking, to waves crashing on a beach near the reef....so even very naturalistic.

 

Macro-algae is sometimes looked at as a swap-in replacement for a skimmer, but at best it's merely similar in some ways....and dramatically different in important ways as well.

 

A skimmer will not dose your tank with organic carbon like algae will.

A skimmer is not capable of "over filtering" a tank the way macro algae can. 

A skimmer does not dose your tank with carbon dioxide when the lights go out like algae will.

 

I'm sure you get the idea....these things complicate usage of algae compared to usage of a protein skimmers. And honestly these things are what makes algae not appropriate for every reef the way a skimmer can be.  Not a drop-in replacement for a skimmer at all really.  More like a different tool that has one or two similar (but different) aspects.

 

Tell us more about the system itself!! 👍😁

[KeTos]

Ok so some background:

 

I was running the system happily for a few years using a Mame overflow and then of course broke said overflow while cleaning it one day. I didn't have the budget to get a new part flown in from Japan at the time so I took my sump offline and just put my skimmer (Tunze 9001) and ato in the display and ran everything that way. So the small refugium in the sump with sand, rubble and cheato went away. Low and behold my whole system went into decline and I started having gha and cyano problems. Everything else had remained the same so I suspect that little refugium was actually doing a lot to keep the system stable and happy.

 

I've been inspired by some amazing tanks on this forum that run only on biological filtration so I thought I'd use this opportunity to do a "do-over" and give it a try. I also have two small kids to chase so not having a skimmer to maintain is one less thing to have to do (although I know this is not a huge amount of work). I removed the skimmer compartment in my sump and I'm turning it into one large refugium with a single divider at the end to make a small section for my return pump. Used some birthday money to finally buy a replacement main pipe for the Mame and hope to have it up and running in the next couple of weeks!

 

Tank is a Mr Aqua 17.1 with a mix of softies and LPS, a pair of clowns, an orchid dottyback and various CUC. Sump is a standard 10 gallon. I'll post some pics soon and also send updates on how it goes, I ultimately decided to do a shallow sand bed in the new fuge. Thanks all for the insight!