Under Substrate Filter

[bizmarty]

Hi all,

Just about to get starting with a marine setup.

I am waiting for my Red Sea Max 250 to turn up, cant wait! :-)

I have a question about taking care of the substrate.
What do you guys think about reverse flow under gravel filters for under the substrate, anyone use them?
What sort of pump do you use for these systems?

I was thinking it would be nice to get the water flowing throughout the substrate keeping it nice and clean.

What systems are out there for people who wish to do this?

Cheers

[rayme07]

Hi Martin to TR. I have never heard of reverse flow under gravel filters before but it sounds neat. Sorry i couldn't help. But no worry's because someone else with experience will chime in soon.

[bizmarty]

Hi Raymond,
Thanks for the reply and warm welcome.
I heard it mentioned in pod cast episode 27 (around the 3mins 20 second mark)
They do sound cool... I think it is a good idea to get the water flowing up through the sand bed.
Interested to see if other people use it.

[Carty]

I imagine this could work but it seems like it would cause problems with water clarity... having all that sand being disturbed... not to mention possibly killing off the filtering ability of the sand

[Phurst]

I'd vote against using any kind of undergravel filter, be it conventional or reverse flow, for a number of reasons. Using one of these systems would require using larger substrate such as crushed coral, which has many disadvantages compared to sand. Additionally, I would imagine a reverse flow UGF would trap a lot of detritus under the plate where it can't easily be removed and would contribute significantly to nitrate issues.

[bbl_nk]

I agree with Pearson here. I think an undergravel is awesome in the freshwater setup and may work in a lightly-stocked fish only marine system, but would go more for using live rock, a deep sand bed, a skimmer and macroalgae as the brunt of your filtration. You can get a sand sifting Gobie to help keep it in good shape. Check out this link on the history of reef filtration: ReefFiltr

[CarmieJo]

Hi bizmarty and to TR!

Do you go by Martin or Marty? My first marine tanks had UGF but that was back in the 80's! I think that you will have far better success with a DSB, LR and a skimmer.

[THEJRC]

If your looking for under substrate for salt water your probably looking at a Jaubert Plenum system. It's a long time before it cycles but studies are showing good results. Not a good system for most hobbyists IMHO as it's quite complex and can backfire if not set up / maintained properly. Given all of the other much simpler means (remote DSB, Skimmers, Berlin system, etc.) most hobbyists have a wealth of styles available that are often better alternatives.

Take a look at the Advanced Aquarist article listed below, it's a good read!

Advanced Aquarist Feature Article

[bizmarty]

Hi bizmarty and to TR!

Do you go by Martin or Marty? My first marine tanks had UGF but that was back in the 80's! I think that you will have far better success with a DSB, LR and a skimmer.

Hi CarmieJo, Martin is fine :-)

Thanks for all of your views and links, much appreciated! So it looks like having an UGF is not such a good idea seeing as this is my first marine setup.

How deep do you suggest I have my sand bed? Going for a reef tank setup with 4 or 5 fish to start (not all at once).

What type of sand bed maintenance do you guys perform (if any)? I was thinking it might be good to stir up a small portion of the sand bed every few weeks or so to move any detritus that is sat there and let the skimmer/filters sort it out?

One more question, the RSM 250 comes with the following filtration system:

Red Sea MAX130D | Filtration & Circulation unit


Mechanical filter sponge
Adjustable protein skimmer with a turbo aspiration pump
Highly porous ceramic biological filter media
Activated carbon chemical filter media
Cartridge for fine (water polishing) filter material
Sponge bubble trap

I was just wondering should I keep the Mechanical filter sponge, Activated carbon chemical filter media and the Cartridge for fine (water polishing) filter material, in place or remove them and replace with live rock? I heard that you do not want a sponge filter in a marine system, don’t know how true that is?

Can I just say I really appreciate any advice from you guys....thanks very much :-)

[rayme07]

How deep do you suggest I have my sand bed?

There are two different types of depths there's a SSB and a DSB. I would suggest going with a DSB because its good for your tank and it makes it look better. I don't know much about sand depths but from what i herd a DSB is the best thing for a marine tank.

What type of sand bed maintenance do you guys perform (if any)? I was thinking it might be good to stir up a small portion of the sand bed every few weeks or so to move any detritus that is sat there and let the skimmer/filters sort it out?

You could do that or you can also get a goby or sand shifting invertebrates like a horse shoe crab or a sand shifting goby and do the work for you plus its very neat to watch. The only maintenance I really do for the sand is get one of those vacuum type things forgot what they are called but get those and clean the sand once in a while. Hope this helps. Thanks

[THEJRC]

deep sand beds are typically 2 1/2 inches or deeper, having them in the display tank verses remote is the latest argument in style that everyone is making. Some prefer lighter sand beds in the display and keep deep sand beds remote for future maintenance helping to avoid having to tear down part of the display down the road should maintenance need to be performed.

I prefer to sit somewhere in the middle for my display with around a 2-3 inch sandbed, stock the tank with plenty of sand stirring critters after about 4-6 months (nassarius snails, cucumbers, sand sifting gobies, etc.) and I stir the sand in many areas to avoid detritus build up. I use a remote tank for my deep sand bed (as well as added water to the system) for various reasons.

The true idea of a deep sand bed though goes against stirring the sand bed. The idea is to create an oxygen free environment within the deeper reaches of the bed. So stirring is a no no. The downside here is that detritus can settle and impact the sand bed as well excess detritus could settle deep within the sand and begin to decay creating an opportunity for the sand bed to go toxic if flow is halted for a long period of time. Hence the idea of building a remote deep sand bed. with a remote DSB one can increase flow within the tank to keep detritus in suspension longer allowing it to break down more. Should flow be cut for an extended period of time or maintenance need to be performed the DSB can be disconnected or turned off and worked on without affecting the rest of the system.

I've seen several successful remote DSB's built using salt buckets, I use a 20 high for mine, but size is not really the main concern here, simply that the sand is deep enough to provide the oxygen free environment and detritus is kept in suspension long enough to break down more before settling.

some good references for you

The Deep Sand Bed - One Of The Most Effective Filtration Methods. | Aquarists Online | Aquarium Fish Resources And Information

Advanced Aquarist's Online Magazine - Feature Article: An Experimental Comparison of Sandbed and Plenum-Based Systems. Part 1: Controlled lab dosing experiments
(really good one comparing the plenum and DSB)

How Sandbeds REALLY Work by Ronald L. Shimek, Ph.D. - Reefkeeping.com
(this is a good one illustrating how sediments work in reefs)

[CarmieJo]

Here is another great article Ron Shimek's Website...Deep Sand Beds by Ron Shimek.

[Carty]

I would also PM amphibious (sp?)

he seems to know a good bit about DSB

[Amphibious]

Thanks for the compliment, Carty.

In THEJRC's post above are links to the "real" experts on DSBs. I have simply followed their advise over the years, experimented a little and came up with a "system" that works for me.

In my DTs I go with 5" layer of pure Bahamian Aragonite sand. In my sump/refugium I go with the maximum depth of sand that allows proper water flow through the device, usually less than 4". So far this is just standard practice. Here's where I differ from the "experts".

I build pipe stands to place my LR on lifting it off the DSB by about 1/2 to 1 inch. This allows water to circulate under the LR keeping it from creating "dead" zones. The second thing I've learned through experimenting is stirring the sand layers of an established DSB does no harm and in fact may help in keeping the DSB from going bad. Actually, I've never had a DSB go bad. My use of DSBs goes back to about 1990. I incorporated the stand pipes around 1996 as an experiment. Somewhere around 2000 I began stirring the DSB. I have never had a DSB go bad and cannot say my deviation in methodology from "accepted practices" of the experts has done any harm. My belief is that those two deviations extends the "life" of the DSB indefinitely.

For those interested in seeing pictures of my method, go to my tank thread - Amphibious' 135 gal reef.

Thanks, I hope this helps.

Dick

[THEJRC]

he he I always look forward to dicks posts, he's got a lot of experience himself for sure (moreso than a lot of reefers out there!). the deviation from standard practice at the bottom of his posts reinforces a lot of my own theories.

While I spend a good deal of time reading and studying "expert" references my favorite thing above all else in this hobby is that theres so much uncovered ground and a ton of room for experimentation and adjustment. regardless of how hard you try, you'll find that after the first year you yourself will have your own tank husbandry "style" all it's own that works for you! Your on the right path already in the way of studying as much as you can about a subject before diving in mish mosh. keep us updated on how you proceed!

[bizmarty]

HI Guys,

Thanks very much for all the comments and links, very informative some good reading there.

Dick, I have the same idea as you about sand bed maintenance, I just seems obvious to me to give the sand bed a light stir up every few weeks or so to get any nasties out for the filters to take care of. Do you stir up small amount of bed or the whole thing? I am definitely going to go for the PVC stands, I like that idea a lot! The only problem I can see me having, is getting 2 or 3 large, flat pieces of LR to use as the base level on the stands, as you know the shapes of rock are generally round (ish). You managed to find some perfect pieces, how did you do that, did you use LR or something else? Also your pictures of the stands showing holes in.... what is inside them, it can’t be stand or it would spill out?

Thanks in advance

Martin

[bizmarty]

Anyone any ideas on what is in those PVC stands?

Cheers

[IAreef]

If I remember correctly they are access holes for small critters, flow etc, the only thing in the stands is the sand that gets displaced as you shove them down in the sand bed, also I believe there are more holes below the sand, but I'm sure someone who definitely knows the answer will chime in soon

[Amphibious]

That's exactly right IAreef. the purpose of the PVC stands is to raise the LR above the sand eliminating dead spots under the LR. I drilled the holes in the PVC to prevent the sand inside the pipe becoming a dead spot and also providing hiding areas for critters.

That picture shows the stands before an additional inch of LS was added. Now, 2 1/2 years later, you can't see the stands.

Dick

[bizmarty]

That's great, thanks for the replies, It must be the way the light is shining on the stands, in the picture above it looks like there is a pipe inside the pipe if you know what I mean! Looking forward to getting set up now!