Barry Grossmans big tank

[mojoreef]

Barry I started a new thread for your tank/ skimmer as it is going to be a good one. So lets get it going.

Barrys post:
I too am interested in big skimmers - need to source build/skimmers for a new 20,000 litre reef tank I just built in Bali and am starting from scratch. I have the ususal plans, books etc but thus far have inclined to a simple venturi set up although could use any qualified advice regarding capacity/size etc....

Idrhawke's post:

I too am interested in big skimmers - need to source build/skimmers for a new 20,000 litre reef tank I just built in Bali and am starting from scratch. I have the ususal plans, books etc but thus far have inclined to a simple venturi set up although could use any qualified advice regarding capacity/size etc....

A 4500 Gal reef tank......are your opening your own Bali Sea World? I think you need to start looking at buying a commerical skimmer or building your own. This may give you some ideas.....Commerical Skimmer

The cheap way to build and operate a large skimmer may be to follow Majorreef's airstone idea, expecially where the size you will need is concerned....as he has said both small compressors and air stone have improved over the last few years. I think you will use a lot less power with an airstone system compared to a pump (ejector/pinwheel) system. We are all waiting to get feed back from Majorreef's experience with airstone life and maintenance.

 

[mojoreef]

IDRHAWKE'S POST:

Here is a more specific approach and idea. If I needed a large skimmer I would look for commercially available tanks that could be modified. As an example; the attached tank turned upside down and a couple of ft. 6" extension pipe added to the cone. Poly tank turned up side down Price and supplier

For the collection cup take a smaller std. tank and cut a 6" hole in the bottom, using a Uniseal to mate, and slip it on the 6" pipe. Small tank for collection cup Price of small collection cup tank Uniseal

The company that manufacturers them may beable to weld and modify the plastic on their basic product to make what you want, or at least suggest someone to do it for you. Adding a good linear piston compressor, airstones and presto a commerical skimmer, it would be a lot cheaper than buying a package made system.

 

[mojoreef]

BARRY'S POST:

hhmmmm.... Nice to get some feed back given that I'm stuck here in the jungle 3/4's through a mad project that can only get more difficult. Thanks fellas and I will come back once I've reviewed the suggested sources.

What kind of tank, well I figured if I was going to do something this nuts might as well go all the way.....as in 'more corals and not so many fish.' That said, gotta have some fish although plans are for some wierdo's like, for example, flashlight fish (see attached JPEG). No, stock is absolutely not a problem here and is very inexpeensive. There are some reasonably serious exporters of stock here and, in any case, we are in a position to source what we want directly from reefs in and around Bali, Slawesi, Java etc...

Yup of course I'd love to use a commercially available big skimmer (like the Deltec AP2601) but the prices are scary! I'm still hoping to find a skimmer solution at under $2500. In any case, I'd like to find a low cost solution that I can share with the aquarium facility at the Zoo in Surabya, Java, They have more than a dozen large tanks but alas they're all but dead and they've no idea how to fix the problem and certainly no funds to do so. (Third world issues you know)

One of the problems I have here is that I can't source large diameter acrylic tubing. I've been thinking about simply using 16in PVC pipe lined inside with Acrylic sheeting (I worry about PVC and algae - all the plumbing is in polypropolyne) for the body of the skimmer unit(s). What I remain confused about is which type of skimmer to use. I had palnned on trying to produce a simple venturi driven skimmer but I worry about the poor little planktons being frced through that little birthing canal every hour or two. Maybe a big but simple counter current skimmer using an airstone and blower?? Or maybe even an ETS/downdraft system?? see...I'm confused.


What concerns me more right now is skimming capacity. Escobal's, Aquatic Systems Engineering, Dimension Engineering Press 1996 probably has the answer but alas my math skills have grown dull over the past few decades. Assuming a moderately efficient skimmer system, would one plan to 'turn' the tank contents every hour (AJ Nilsen), every 3 to 4 hours (as appears with some of the Deltec skimmer specs) or less frequently?

Anyway, any and all advice is appreciated and I will now go and follow up the suggested sources...Thanks Mike & LDRH

 

[mojoreef]

NIKKIS'S POST:

I have a question.... Does a skimmer have to be tube/cylindrical shaped? If acrylic tubing is difficult to get, but acrylic sheets are not.....could a skimmer have a tall square-shaped body? I don't know how efficiency would be effected, but with the airstones like Mike has, would it make a difference?

 

[mojoreef]

IDRHAWKS POST:

hhmmmm.... Nice to get some feed back given that I'm stuck here in the jungle 3/4's through a mad project that can only get more difficult. Thanks fellas and I will come back once I've reviewed the suggested sources. ...............................

One of the problems I have here is that I can't source large diameter acrylic tubing. I've been thinking about simply using 16in PVC pipe lined inside with Acrylic sheeting (I worry about PVC and algae - all the plumbing is in polypropolyne) for the body of the skimmer unit(s). What I remain confused about is which type of skimmer to use. I had palnned on trying to produce a simple venturi driven skimmer but I worry about the poor little planktons being frced through that little birthing canal every hour or two. Maybe a big but simple counter current skimmer using an airstone and blower?? Or maybe even an ETS/downdraft system?? see...I'm confused.

....................... Assuming a moderately efficient skimmer system, would one plan to 'turn' the tank contents every hour (AJ Nilsen), every 3 to 4 hours (as appears with some of the Deltec skimmer specs) or less frequently?

Anyway, any and all advice is appreciated and I will now go and follow up the suggested sources...Thanks Mike & LDRH

Mike,

I wouldn't worry about hurting the plankton, especially with as large a pump as you will need to feed and recirculate with. The theory of plankton being hurt from going through a centrifugal pump is largely a bunch theorectical bunk. If you could get a large microscope, I'd bet you'd see the plankton smiling as they came out the other end; as if they just went to Disney World and came off a roller coaster ride.....

Keep one thing in mind,....you can only undersize a skimmer. After couple of weeks, after giving it and the tank time to stablize, that is easy to figure out. Does you skimmate stop or slow down as the skimmer pulls out the protein from the life load. If it just continues to pull skimmate without stopping, it is undersized.

When I feed my skimmer pulls out the residual protein within an hour and fills my container. It pulls out very little between feedings. Too small a skimmer pulls out protein slowly and give the proteins a chance to break down and pollute the water.

Virtually all plastic material is inert to salt water and can be used for construction as long as it has the structural strength to hold the pressure.

Stop when you see a construction site laying water and sewer pipe. Ask the forman for a piece of scrap and pay him a few bucks. Large PVC or poly pipe used in contructing sewer and water lines is ideal. Keep you eyes out for any place they are laying new water or sewer pipe to pick up a 6' section of scrap to use to build a skimmer. It doesn't need to be clear, infact clear encourage algae growth inside. If you can pick up plastic sheeting to make a square shape skimmer that is fine too.

A skimmer is the easiest piece of equipment you can build. All you want to design for is fine bubbles, contact time, and flow rates. Just copy the basic dimensions used for one of the large commercial systems. Taller is better.

Also, a skimmer doesn't have to be a single large unit; it can just as easily be multiple smaller units sitting side by side and run parallel. If you can only find cheap 6" or 12" pvc pipe to build it with; install three or four identical smaller systems side by side with a single feed pump. The nice thing about that is you can easily increase capacity by adding another section in parallel.

The cheapest way from both the component and operating cost stand point is using a good little linear compressor and airstones, like Majoreef has done. Just pick a quiet compressor so you don't have to put it a 100' feet away because of the noise. :badgrin: You can always design it and install connections so you add an ejector and pump to test out other feed systems. Just keep a gallon of vinegar around with replacement air stones soaking in it. Design the skimmer so the airstones are easy to remove and clean.

If you live close enough to the water, buy a good pump and lay some piping. Then you can forget about all this skimmer stuff. Good luck and post pictures......

 

[mojoreef]

Good post Idrhawke!!

Barry I think for a tank that sie we should take a slightly different approach when dealing with this tank. Once you get into the size and scale of what you are planning you really need to change from conventional methods. As per acrylic, that is going to be the front face of the tank, beyond that it would be best to look at alturnative materials. In tanks of this size polypropolyne is your friend
Look to getting polypropolyne drums and or containers, they should be easier to get in bali, source some of the collection stations and aquaculture facilities in Bali, for where they are getting thier products and then maybe piggy back.
As per plankton I would not worry about that at all, on testing of reef aquariums it show very tiny if anything in water column, actually most planktonic life in the water column is stuff you want to remove. I would lean towards a decent sized skimmer enhanced with ozone.

I will come back in a bit and try to get some details out for ya.


Mike

 

[piercho]

Hmm. Well, a couple of comments with regards to using air. I've been using linear compressors (MEDO AC602's) continuously for 3 years to provide my skimming (CC) and roughly 1/2 of my water movement. So just know that is the basis of my experience with using air in reef tanks, and some of what will follow is speculation not based on experience.

1st off, their are several types of "serious" air sources, none of which is ideal for every situation. Aquatic Eco Systems has a very good catalog to help you sort out which air source is best for your needs if you decide to use air.

Blowers have been mentioned. Blowers, generally, move lots of air but at low head. So a blower application would (typically) be for 2'-3' water lift pipes (pumps). For a tank of this size, IMO, a blower powered lift setup may be a good way to do your bulk water movement, because lifts are efficient and because you can use the air to help cool the water. The air has to be pre-cooled (its hot coming out of the blower) if you want to cool the water, for your climate this is typically done by running the piping between the source and the load through the earth, using the earth as a heat sink. A disadvantage of using air is that the lift function is usually accomplished in an adjacent tank (a "collection" tank, from Spotte), so that the spray and bubbles from the lifts are contained in that tank. The collection tank takes up space and needs large-diameter interface plumbing. Another advantage of using lifts is that a Reverse Carlson Surge Device (RCSD) can be put on the same air source. When the RCSD fires, the lifts turn off, and then ramp up flow as the RCSD fills with air. This provides dynamic water movement without the complication and expense of mechanical rotating return heads or switching ball valves. Another advantage of the RCSD+lift arraingement is that the backflow of the lift injectors when they flood (when the RCSD fires) makes them completely maintenance free because no biologic or carbonate deposits can accumulate at the injection holes. I know you are interested in skimmers, but when (big) air sources are brought into a conversation I tend to bring up water movement with air, because this is what I do. Anyway, if this is of interest to you, I have a .pdf I share with people showing my RCSD + air lift arrangement.

On to skimmers. Unfortunately, I don't know how Mike is using air with his skimmer, so some of this may be redundant. 1st, lets consider air sources. Linear compressors are great for skimmer applications because they respond well to increases in head pressure. In other words, a 5' injection head plus moderate diffusor pressure is well withing the optimal output curve of a good linear compressor like a Medo. However, I think you are talking about a mucho big skimmer so an alternate source like a vane compressor may be a better source. These have some maintenance (annual vane replacement) but look like good sources for higher air volumes at moderate pressures, to me.

Now, diffusors. Them little bored pieces of limewood just don't hack sh#t, excuse my french. Even with many placed parallel, the backpressure on the pump is too high and WHAT a waste of wood and space. What you need is lots and lots of Bubble Producing Surface Area (BPSA). For my skimmer, I use a wet-glued diffusor known as "KW's awesome air diffusor" popularized by Jon (Snailman). These are constructed from panes of Basswood, presoaked to preswell (so they don't crack when placed in water) and glued together with cyanoacrylate to form a box. For my relatively small 6' X4" skimmer, I make the biggest box diffusor that will fit down it, and it will easily last over a year as long as its kept continuously wet and has air supplied to it (nearly) constantly.

As far as clear pipe (clear PVC or acrylic), you need very little for skimmer construction. I use ABS for the reactor body and clear pipe just for the riser pipe and part of the collection cup so that I can see to adjust the input water and air flow. With clear reactor bodies, you can see the air blooming in the reactor body, but this serves no purpose (except to look cool), and allows alga growth iniside the skimmer. As well as the poly drums Mike mentioned, you might also look for commercial-sized (6" and over) ABS or PVC pipe like is used for sewer systems for body construction. Construction crews will have sections left over that they may be willing to part with at the end of a job, or you can buy full-length pipe from a commercial supplier and cut it to size.

I've considered adding injection of ozone many times with my skimmer. I just don't think the expense of the ozone generator is justified for my system volume (~100G). However, for a big system, I think it would be economical, and provide a good way to help improve clarity as well as reduce the total volume of skimmers used.

Some final notes on air skimmers. An air injected skimmer can produce a relatively tall standing foam head compared to venturi skimmers, especially as air injection approaches saturation. So plan to make the skimmer relatively tall. Also, provide yourself with a decent way to regulate air injection. I use a 1/4" commercial quality needle valve on my skimmer, sort of expensive but trying to set air with a ball valve will make you tear your hair out.

 

[mojoreef]

Howard great post!!

I have seen snailmans diffusors, they are effective but I dont think they line up with the new heat bonded glass diffusors available now. The bubble size is 100 microns and the lifespan and clean ability of them can be beat. Check the aquatic ecosystems catalog for the sweet water fine pore diffusors.

Mike

 

[Barry Grossman]

wow...thanks for the response everyone. I think I'll post ome pics and plans later this afternoon to give a little perspective.

 

[piercho]

Mike, I'd be happy to give the AES ceramic diffusors a shot. I tried a fine pore diffusor (not AES) a couple of years back and was happy with it until I tried the KW, which cut my back pressure way back. But having to make the KW on an as-need basis, then keep it wet and pressurized can be a pain. I just got an order from AES a couple of weeks back, so it may be a few months, but I'll try them.

 

[edgerat]

the sweet water diffusers(page 278 of Aquatic Eco-systems master catalog) are actually made of glass that is bonded together.

 

[ldrhawke]

As Mike has eluded to, one of the big problems using an air compressor is the air diffusors is maintenance. The small amount of dust in the air can quickly cause havoc and blind the diffusor from the inside out . Mike's idea of putting a shop vac filter on the inlet to extend diffussor life is a great idea. Another idea is to simply build a wood box to set the compressor into and make the top of the box the size of a std furnace filter; so you can simply set a high quality rectangular HEPA type AC filter, the pleated type by 3M, on top of it to filter the air. If you bought a cheaper noisier compressor, the box could also be built to dampen sound using sound proofing material on the box walls and bottom.

 

[ldrhawke]

Compressed air skimmer design thoughts.......

I always design systems as if I had to do the maintenance myself. If I was building an air skimmer knowing I needed regular access to the air stones to clean and replace, I would do the following.....

Obviously install a shutoff and drain valve to isolated the skimmer from the tank head pressure to give you access to the diffussors. All the water in the skimmer would need to be drained so this would normally be done as part of a regular water change.

Next I would make the diffussors easily accessable by installing multiple unions unions around the circumference of bottom of the skimmer. Or, they could all be placed on one side if the skimmer was against a wall.

One union for every diffussor stone so that the airstones could be threaded onto a piece of pvc pipe onto half of the union that you remove. That half of the union would have a couple of foot of hose connection to the air supply, for easy removal or insertion of the diffussors by simply undoing the oring-union connection.

The diffussor's could be long with a lot of surface area, nearly the diameter of the skimmer using this method. Also you could mount as many diffusors as you like, every so many degrees, around the circumference of the skimmer bottom. :razz:

These same union connections could also for a pump ejector system connections if you decided to change your aeration design. :doubt:

 

[ldrhawke]

ALSO...... I would mount the air compressor above the static liquid level inside the skimmer. A low pressure drop swing or ball check valve is nice, but they will leak at some point. Otherwise, you have the potential of draining your whole system back through the compressor if you lost power.

 

[mojoreef]

Good ideas!

I would mount the air compressor above the static liquid level inside the skimmer. A low pressure drop swing or ball check valve is nice, but they will leak at some point. Otherwise, you have the potential of draining your whole system back through the compressor if you lost power.

Very Important!!!!!!! trust me it happened to me on the second day. Filled the air pump with water. I got lucky and was able to drain it and use a hair drier, and it was back in biz, but not somethinng I would like to see again.

 

[piercho]

Another idea is to simply build a wood box to set the compressor into and make the top of the box the size of a std furnace filter; so you can simply set a high quality rectangular HEPA type AC filter, the pleated type by 3M, on top of it to filter the air.

This is exactly what I do. I use a cooler for an enclosure, and a small 3M HEPA furnace filter. As well as extend the life of the diffusor, I speculate that it also extends the life of the linear piston by reducing abrasives that make it to the pump. Since the pumps don't draw that much air (compared to a house air handler), even a small air filter (area wise) will last a long time. One thing to keep in mind when enclosing the pump is that it will loose its normal heat loss path. So, the enclosure may need to be ventilated, which is what is true in my case. So, the enclosure is separated into an air inlet area (where the filter is), with air pulled from here by the Medo pumps through the 1/2" inlet fittings. A 4" fan ventilates the area where the Medos are. One time the vent fan failed, the MEdos continued to operate but lost their head pressure. When I figured it out, I thought: "Great, now I've ruined two pumPs". Cracked the enclosure lid, the pumps cooled down and were up to operating pressure again quickly. I really like these Medos.

As far as not backflooding the pump, I loop the main air feed lines up higher than the water level of the loads. This has been adequite to prevent siphoning on loss of power in my setup. Setting the pumps physically higher is best, but not practical for me.

 

[ldrhawke]

This is exactly what I do. I use a cooler for an enclosure, and a small 3M HEPA furnace filter. As well as extend the life of the diffusor, I speculate that it also extends the life of the linear piston by reducing abrasives that make it to the pump. Since the pumps don't draw that much air (compared to a house air handler), even a small air filter (area wise) will last a long time. One thing to keep in mind when enclosing the pump is that it will loose its normal heat loss path. So, the enclosure may need to be ventilated, which is what is true in my case. So, the enclosure is separated into an air inlet area (where the filter is), with air pulled from here by the Medo pumps through the 1/2" inlet fittings. A 4" fan ventilates the area where the Medos are. One time the vent fan failed, the MEdos continued to operate but lost their head pressure. When I figured it out, I thought: "Great, now I've ruined two pumPs". Cracked the enclosure lid, the pumps cooled down and were up to operating pressure again quickly. I really like these Medos.

As far as not backflooding the pump, I loop the main air feed lines up higher than the water level of the loads. This has been adequite to prevent siphoning on loss of power in my setup. Setting the pumps physically higher is best, but not practical for me.

Great mines think alike...... :badgrin:

Good point on the box ventilation.... I used a thermos box with a small maxijet to hold a couple of coral over night one once, partially closing the lid when I went to bed. Those coolers retain heat very well....the water had to be over 120 degrees the next morning and the coral were cooked.

Another and an even simplier approach for an enclosure would be five small HEP filters and duct tape to make a box to set over the compressor. It would allow for heat dissipation. :idea:

 

[Barry Grossman]

Bali tank

Gidday all! So the pics below (click on the thumbs) show the tank as it stands today. On either side of it are equipment rooms that measure about 2m long x 1.20m wide and 3.5m high.



Underneath is a sump that runs the length of the tank and with access points from one side (man hole size) and from the front. I do not yet have a plan as to how I will utilize the sump. The literature I’ve looked at all has swayed me away from using any sort of filter media in the sump apart from broken up dead coral. Any contrary views??

There is about a 2.5 meter drop from the overflow to the sump manhole in the left side equipment room. Anyone have any thoughts on using an ETS type skimmer between the over flow and sump manhole, followed by a second downdraft type skimmer on the other side of the tank?

Apart from skimmer(s) and whatever is set up in the sump, the plan to date only calls for two further tanks, one containing activated carbon and the other silica, to be used as warranted.

Lastly the plan calls for a UV sterilizer unit for zapping new sea water and a RO unit for topping up with fresh water. Ozone would be better buts alas too many $$$ unless I'm missing something.

The tank itself drops some 25cm below the viewing pane and I thought I would fill the tank with that much live sand and probably 2 to 3 cubic meters of live rock. The returning water will be injected from the left and right sides of the tank using an alternating timer in order to hopefully create some sort of water circulation /movement in the tank.

Most of the light requirements will be provided by natural light. The tank has a 1.5 meter high glass structure of the top of it with full northerly exposure. We are located just below (to the south) of the equator. In addition there are 6 - 400 watt 20000k blue MH units and 4 double 1.5 meter fluorescent units. The MH units are positioned about 3ocm above water level.



That said, I worry that the tank is too deep-2.5 meters for the available lighting. I’m also worried that I’ll have trouble keeping the water temperature below 23c even though the viewing panel is in a centrally air conditioned room. I though I might put a small AC unit in the glass structure above the tank but I’m not sure that it would be enough to counter the effects of natural exposure to the sun and heat generated artificial lights. The average temperature here year round is 28 to 30c and never really drops below 25. I had contemplated using underground piping as a chiller in the manner suggested by Piercho but don’t have anyplace to do that. The only alternative I can think of is shipping some titanium pipe from over your way and making a chiller in the sump using air conditioning spare parts.


Have read and considered everyone’s posts. Lots of helpful hints and points regarding position of the compressor and heat, noise and dust issues all noted. This will save me a lot of grief! Is there any consensus as to the best type of diffuser to use: KW, bonded glass , ceramic or other??

Anyway, I appreciate everybody’s interest and advice so far and will consider any advice given.

Barry

 

[ldrhawke]

Send pics of sump and equipment room......

 

[mojoreef]

Ahhh Barry you got to love a person that goes for it. Good for you.

As per lighting I would not worry to much about it. The volume of water you have should allow you to run a sucessful mixed tank as long as you dont get the nasty soft corals. So just keep the light demanding stuff high and go with some passive soft and lps a little lower in the tank.

On the skimmer and sump area I would go with a something a little different. I would have the drain water go directly into a skimmer (air stone running about 4 cfm), from their draining directly into a second chamber of the sump with a carbon tray. you can make the skimmer out of polypropalene and then trick it out to be a self cleaner.
On the UV you can do that as it will create some ozone anyway, the main thing you have to do is to have some type of filter socks or simular to collect the organisms that you kill with the uv, or they will just end up rottening in the tank.
On the temp thing, possibly look to modifing a fridge?? if a chiller is not available.

I will come back a little later


Mike