Plenum Construction

[Alentino]

I have read that to construct a plenum, one has to use somethin like an egg crate material supported by pvc supports underneath and a layer of fibreglass screen to create a void in the bottom of a tank. and next would be filling the top with a layer of coarse gravel before screening with yet another fibreglass before finally topping up with a layer of fine sand.

ok my question is is it ok if i forfeit the 2nd layer of screening and fine sand? just a layer of crushed coral over the egg crate and screen.

2nd question is what if i can't find the fibreglass material but use pvc screen which is also used to keep out mosquitoes in windows?]

thanks in advance

[Tanzy]

Any netting of the correct size will do.

You don't use coarse sand for plenum. It should be #1-#3 crushed coral.

If you do not use a second netting about 2" from the surface, you will risk the plenum being excavated and anoxic region being disturbed by digging animals or crazy powerheads.

[Achilles Tang]

Why don't u just do a straightforward DSB? It functions the same without the hassle.

[Alentino]

thanks for the advice Tanzy. but i'm not sure how grade 1-3 sand looks like but i just used the common crushed coral sand that can be seen in P#t sh#p boys. what grade is that? plus i constructed the plenum in my sump tank after being fed up with nitrates. i was told that some people used plenums in sump so i gave it a shot. hence i don't have to worry bout burrowing animals or stuffs cuz its empty there. would that setup be fine?

[expat701]

Have you considered a Mud Filter/Refugium??? I think the general feeling within the hobby today is that DSBs are perferable to Plenums (even in the sump). More and more people are trying Refugiums with and without DSBs in their display tanks.

I'm putting together a hybrid at the moment. I'm using a shallow sand bed (.5 inch for display only), lots of live rock (good quality Fiji rock) and hang-on skimmer and refugium (skimmer and refugium are a single combined hang-on unit). I'll be using Kent Marine Biosediment in the refugium and lighting it opposite to the display tank.

I'm hoping the rock, skimmer, mud sediment and the algae export will work together to keep nitrites and nitrates down.

[Tanzy]

Just ask the retailer what the size of the sand is or request specifically for the correct size.

[dodo]

Fiji LR dun come cheap although they looks really nice.

Wonder wea in SG sell Fiji LR...even if they claim it is Fiji, dun thk we can verify unless u see Fiji LR b4. IMO, local LR is good enuf. Better to invest in a good skimmer & a workable refugium.

Edited September 4, 2003 by dodo

[expat701]

I've looked at rock from the Phillipines, Indonesia and Fiji. The Fiji rock impressed me for a few reasons... it's beautiful, light, porous and they cure it using saltwater sprays that helps get rid of a lot of pests from the rocks (M Shrimps, crabs etc). It's $12-16 per kg. Worth it IMO.

Hybrid means - mixture. I'm building a mixture (hybrid) of the Berlin and Ecosystem method of reef keeping.

I am actually using a hang-on skimmer that includes a refugium chamber after the skimmer. It's a new product made by an Australian company. I actually helped them design it. It's sort of like a CPR BakPak Skimmer and CPR AquFuge refugium combined. Very cool IMO. It saves me needing a sump tank (at least for now).

[dodo]

$12-$16 nowadays for Fiji LR is cheap nowadays....i remember not too long ago, somewea is seliing for $25/kg

hope it means SGD

u help the australian co. to design a hangon skimmer/refugium.

u residing in australia?

[Cookiemunster]

I've looked at rock from the Phillipines, Indonesia and Fiji. The Fiji rock impressed me for a few reasons... it's beautiful, light, porous and they cure it using saltwater sprays that helps get rid of a lot of pests from the rocks (M Shrimps, crabs etc). It's $12-16 per kg. Worth it IMO.

Hybrid means - mixture. I'm building a mixture (hybrid) of the Berlin and Ecosystem method of reef keeping.

I am actually using a hang-on skimmer that includes a refugium chamber after the skimmer. It's a new product made by an Australian company. I actually helped them design it. It's sort of like a CPR BakPak Skimmer and CPR AquFuge refugium combined. Very cool IMO. It saves me needing a sump tank (at least for now).

Hi expat,

where in singapore did you see fiji live rock? If its really fiji, and its light and porous, it would make better live rock compared to local ones and at the price of $12-$16 is a really good deal.

Alentino,

as what AT said, plenums are not necessary, a DSB of >4inch works equally well if not better.

If you really want to do plenum make sure you build a good one that can last. Mistakes made and it will become a normal DSB. You will need to use really fine mesh to completely wrap around the entire eggcrate. In between the 2 eggcrates, cut several 1/4 inch pipes and lay them horizontally. Make sure they are sufficiently spaced as you are going to place live rock and sand ontop. Any weak spots and the rocks will cave in and topple whatever structure you made.

Another layer mesh above the grade #1 to #3 sand is needed as Tanzy mentioned and this is very important. On top of this layered mesh, you can place grade #0 sand.

From what I've read, a plenum can only last 2 yrs before it becomes useless. Back to DSB. Cos the plastics crack, mesh disintegrates and sand starts filling up the water space.

[expat701]

Nope... I'm Australian but I've lived in Asia for most of the last 10 years. This is the 3rd time I've lived in Singapore. Been back here now about 18 months. It's taken me this long to get around to setting up a tank.

And yes, i helped design it. They had another product that is a hang-on skimmer with a filter. The water is filtered post skimmer. I realised the design could be modified to provide a Refugium post skimmer instead of a filter. I contacted the owner of the company and I sent him a design based on his original product. He was interested to build one. We worked back and forth (mainly email) until the protype was finished. They've not gone into production yet. It's a win win - he gets a new product line and I get what I wanted... I can give more information if anyones interested.

[Tanzy]

On top of this layered mesh, you can place grade #0 sand.

You cannot use #0 sand with a plenum. The sand particles will settle downwards and get through the netting. The smallest is #1 and some fine dust will still get through into the plenum space.

My plenum is 4+ years old and still running strong.

[expat701]

Saw the Fiji rock at a shop on Balestier Rd, i think they are called Paradise R**f. They are on the corner, I think it's no 1.

First batch i saw was $12 kg... I was there on the weekend and they had a new batch at $16 kg. Nice rock.

[dodo]

From what I've read, a plenum can only last 2 yrs before it becomes useless. Back to DSB. Cos the plastics crack, mesh disintegrates and sand starts filling up the water space.

From wat i had read & deduce, it is the DSB tat can last only 2years (RC)

OK...let's not start another berlin, DSB or plenum battle here. I believe everyone has their own views & hopefully everyone gives a little respect to someone's view(rather than indirectly condenming their setup)

expat, i saw those LR at the LFS balestier road...was not very impressed, i think those at CF a while ago looks much more nicer & 'cured'.no wonder they are selling at $25/kg previously

i hope to see your design to tat australian company.any chance to see a pic of it?

[expat701]

This should really go under the Equipment forum... but anyway...

My new tank is small (35 US gallons). I was looking for a hang-on skimmer to use on it. I was going to buy a Prizm but changed my mind...

AKS are a manufacturer in Australia who make good skimmers and overflow boxes.

I was going to buy their model BIO SKIM 2000 MODEL TB1 for my tank.

Their web is http://www.aks.net.au.

The model I originally thought of buying can be seen at the bottom of this URL:-

http://www.aks.net.au/bioskim2000.html

But when I looked at the design I realised it would not take a lot of work to make it into a skimmer with refugium.

I emailed them with a design based on this model. We worked out the details via emails back and forth.

I'm attaching a pic of the prototype that is being sent up to me now.

AKS will sell them direct into Singapore as they don't have a dealer over here. The price for this unit will possibly be around $300 Singapore (including shipping) when it goes into production. Price is still to be determined. They are waiting for me to fully test the protype before putting it into full production.

Dimensions are as follows:-

Height 400 mm

Width 95 mm

Length 400 mm

Refugium chamber dimensuions 200 mm x 95 mm x 300 mm high

I spoke to them today... they are happy to take inquiries from Singapore.

BTW I have no affiliation with this company. I've not even met them in person. My only interest was to get what I wanted at a resonable price.

*Photo resized by Admin*

Edited September 4, 2003 by Achilles Tang

[Alentino]

wow thanks

speakin of Fiji liverocks.... the live rocks i had in my tank were all harvested from sabah p. sidapan on my snorkelling trips. i live in sabah. the rocks there were also beautiful, reddish/purpulish throughout cuz encrusted with coralline algae. what are the colours of Fiji live rocks?

[expat701]

sorry the pic was bigger than I thought... it's almost life size.

[Alentino]

Hi expat701,

you mean this design should work good as a convenient refugium ###### skimming? its just like an external sump except that its a convenient hang-on isn't it?

[expat701]

Correct. It's a hang-on. The skimmer is powered by a pump/powerhead 1200 l/hr. After skimming the water passes thru a sponge (remove bubbles) and across the refugium chamber. Water flows at about 300-400 l/hr once it leaves the skimmer. After the refugium the water passes thru some bio balls (mainly to act as a mechanical filter and trap large algae particles etc) and into the display tank. The unit shown has a removable lid. I will run it without the lid. The design was based on some of the ecosystem (miracle mud) sumps I've seen.

[Achilles Tang]

Hi expat701, pls keep photo width to 700 pixels wide!

Resized correctly for you!

[expat701]

Thanks - I was worried when I saw how big it posted...

[Cookiemunster]

Thanks - I was worried when I saw how big it posted...

Bro thats a great looking design. But some personal comments. It would be great if the sponge filter could be bigger as that would most likely clog up in a week.

Also the use of bioballs is not recommended as this would be a nitrate factory. It would be better to leave that compartment for more sponges or to incorporate a skimmer in there (dunno if that would be possible or not).

I have been looking for a good hang on filter mainly as a mechanical filter filled with sponge or cotton fibre for trapping ditritus. The best designed one was eheim liberty but I had a big problem with splashing. Cos it would wet everything especially the lights. Hence I switched to using a top trickle filter (common brands are taiwanese such as Dolphin etc but I chose a japanese made one). I filled it with cotton fibre instead. It still had splashing problem but alot less than the eheim.

However now I need to find a surface skimmer to clean the surface of the water.

Oops sorry I've gone off topic. Perhaps a new thread can be started?

[expat701]

Cookiemunster, I think you may be missing the point here with this design and the overall function of this "filter"...

Firstly it's not a hang-on filter like a Eheim Liberty. It's an efficent protein skimmer coupled with a refugium. As designed the refugium leans towards being a mud filter. But need not contain mud... could contain sand, LR whatever.

First stage is an efficient protein skimmer. This would remove most of the particles which you believe would clog up the sponge. The water comes straight out of the skimmer into the sponge. The sponge is actually there to trap bubbles not act as a mechanical filter as such... also the sponge can be removed in seconds if someone doesn't want to use it.

The bio balls are there to stop algae flowing back into the display aquarium. They are completely wet (not exposed to oxygen as they would be in a wet dry/trickle filter). As well there are not many off them. Hence not as efficient biological filtration as a wet dry (lack of efficiency means less nitrates). They would hardly create much in the way of nitrate... but even if they do the nitrate will feed the algae in the refugium. Again, the balls can be removed in seconds if not wanted.

The following link from ecosystem aquariums shows their recommended refugium setup for running "Miracle Mud", the design is similar:-

http://www.ecosystemaquarium.com/html/mira...pplication.html

Again, it's designed primarily as a combined protein skimmer and refugium mud filter for small to medium reef tanks (up to say 50 us gal). The media can be removed at will.

[Alentino]

ok, so what about it's use in bigger tank? would'nt it be better for a bigger sump to be installed since a larger volume of water has much more advantages like dilution and stability in other parameters? how'bout surface area?

[expat701]

On a tank larger than 50 gallons, a larger remote sump with a refugium would be preferable.