Overskimming??? (Lengthy)

[Garry thomas]

As i said what a can of worms? i quote NO REEF TANK CAN assimilate the movements on a natural reef? or something lilke that? it is late on a sat? i dont agree. i have for one similair currents to a real reef, so why no one else? and why you quoting Turbitidy with skimming?

 

[ChrisRD]

What about the use of LR and DSBs? Don't these try to imitate the ocean?

Yes, and as you stated earlier:

I don't think skimming happens in nature by wave action nearly as much as in our tanks.

I would say the same applies to the filtration provided by live rock and sand. I think the major nutrient export mechanism around a natural reef is probably dilution.

I think we have to use more intensive methods of export in our tanks because of the great differences in scale. We're dealing with a small closed system, so pollutants are in much higher concentration.

FWIW, most of what's been stated in this thread makes a lot of sense to me - many excellent points have been brought up. I'm not debating the whole skimmer/skimmerless thing, and I'm not saying it's not possible to overskim a tank. I just don't think the original poster is overskimming his 65 gallon tank with a hang-on skimmer. IME they're pretty inefficient...

 

[Garry thomas]

Wolfman i must agree these so called cheap skimmers are pretty basic items which really dont do a lot anyway, i have a cheapy on my quarantine tank 40 gals, its a seaclone run by a maxijet p/h basically
ITS CRAP......right im not having a dig at people with seaclones, im just trying to get the point across, that until you have a proper skimmer you dont realise until then that these cheapies are crap. get a quality skimmer and watch your tank improve?

 

[Minh Nguyen]

I have a 65 Gallon tank, 1"cc, approx 80 lbs LR, 2 penguin 650 Powerheads, Precision Marine HOT-1 skimmer, (2) 30 watt Triton and (1) 30 watt Blue Moon bulbs. Short on light, I know, working on a canopy with PC's. Lights on 14 hours a day. Only current residents are 20 Blue leg hermits, 6 Astreas (12 recently died), .........
........Hermits and shrimp doing fine, Snails kind of lathargic (maybe not getting enough to eat? Maybe that's why the others died?).

Question is, could I be overskimming the tank? And, for the sake of debate, is it possible to overskim a tank at all. I always thought it wasn't, but am not so sure.

Would very much like your input!

Dave

Dave,
You can over skim a tank. As some of the above post mention, specially if you are setting up a lagoon type tank with solf corals and LPS. A reefcrest type set up, it is harder to over skim as the water there is very poor in disolve nutrients.
IME, your snails maybe kill by the hermit crabs. I anly have 3 hermit crabs in my 450 g tank. 20 in your 65 g is, IMO, way too much. The other problem is that snails have parasitic snails also. They look identicla to the snails that prey on giant clams but is higly specific on snails and will not infect your cmals if you have any. These snails can easily be seen if you look for them when your snails are on the front glass.
You man not have any, but if you do, you will need to remove them or they will weaken and kill your snails.
Good luck.
Minh Nguyen

 

[madrefkepr]

Thanks, everyone. Some very good advise here. I realize there are much better skimmers, but not having a sump, I am somewhat limited? The setup I have is an "experiment". I am working on a very limited budget, for aquarium anyway. I am learning a lot in a very short time. Next time I'll do it right ! Next step for me is to remove cc and add sand. Anyway, everyone have a happy holiday!

Dave

 

[wombat1]

I think he'll be fine with the skimmer he has. He also asked, strictly for debate, if it was possible to overskim a tank. I think it is.

I would say the same applies to the filtration provided by live rock and sand. I think the major nutrient export mechanism around a natural reef is probably dilution.

This is definitely the case on the reef crest, but that water has to be filtered eventually. A lot of that filtering is done by the animals and plants in and on the rock and sand on the reef and further inshore. Here's a good thread if anyone's interested.
www.reefcentral.com/vbulletin/showthrea ... genumber=1 The good stuff is towards the end on page 6 or so...

 

[wombat1]

Garry, your tank is awesome. You wrote

i dont agree. i have for one similair currents to a real reef,

How many times an hour is your tank volume turned over? I think it's pretty tough to come anywhere near the water movement on a natural reef. My water goes through about 400 gph on my 30 gallon tank (about 13X) and that's hardly enough.

 

[ChrisRD]

I realize there are much better skimmers, but not having a sump, I am somewhat limited?

IMO the hang-on skimmer you have is one of the best available. FWIW, I've had several setups over the years with no sump that did fine. It's not a must (although I prefer having one). We've seen plenty of pics of great "sumpless" tanks on this board.

The setup I have is an "experiment". I am working on a very limited budget, for aquarium anyway. I am learning a lot in a very short time. Next time I'll do it right ! Next step for me is to remove cc and add sand. Anyway, everyone have a happy holiday!

LOL - every setup I've had is an "experiment". I think one of the fascinations with this hobby is that there seems to be an endless amount to learn (of course, some months you feel like you went backwards!! ).

Dave, your setup sounds fine. Sounds like everything is going well so far. I think you have a light bioload and you're not seeing much algae growth because things have reached an equilibrium.

BTW, Happy Holidays to you as well!!

 

[ChrisRD]

A lot of that filtering is done by the animals and plants in and on the rock and sand on the reef and further inshore.

Do you have any specific information on how much of this water is "filtered" locally (on/around the reef) vs. how much is just washed away? I'd be interested to learn more about this.

 

[Anonymous]

To the person who asked why I run a skimmer when some of my tanks do fine with out them...
Because it eases my maintinence routine, and I like the margin of error it provides me. I do however tend to run skimmers that are smaller than what most would run on a given tank. It's a good compromise I think...
Cheers
Jim

 

[madrefkepr]

Thanks for the vote of confidence, Wolfman! I was beginning to think I was the only one that has even seen this skimmer ! Removed cc today, and added 1" sand. Maybe I'll be able to see how I arranged the rock sometime after Christmas, because I sure can't see anything now 8O !

Thanks again, to everyone! This has been an interesting topic. Maybe I'll stir things up again after the holidays!

Happy Holidays!

Dave

 

[wombat1]

From an article at www.seabay.org/art_plenums_part1.htm by Rob Toonen:

in nature, the recycling of nutrients (such as nitrogenous wastes released by fish and corals) is accomplished largely by the seagrass beds and mangrove lagoons typically adjacent to reef areas (Lowrie & Borneman 1998, Toonen 1998-99). Lowrie and Borneman (1998) provide this quote from Ogden (1988) to illustrate the importance of interaction between coral reefs and the adjacent communities to the existence and persistence of coral reefs: "Mangrove and seagrass systems are sinks, trapping and accumulating organic and inorganic material and permitting the growth of coral reefs offshore (while) coral reefs buffer the physical influence of the ocean and permit the development...of lagoon and sedimentary environments suitable for mangroves and seagrasses."

Wolfman, I know this doesn't entirely answer your question about how much waste is filtered and how much is simply washed away into the ocean by dilution. I assume that most of of it is pushed onshore. I couldn't find any specific numbers, but I think this is good evidence to show that a lot of filtering is done by the near shore animal and plant communities. It's a great article along with www.seabay.org/art_plenums_part2.htm that really goes into detail about sandbed ecosystems.

 

[wombat1]

This is from an article by Ron Shimek:

Hamner, et al. 1988. Zooplankton, planktivorous fish and water currents on a windward reef face, Great Barrier Reef, Australia. Bulletin of Marine Science. 42:459-478.

The water flow over a reef was calculated at: 6,000 cubic meters of water/1 linear m of reef crest in 12 hr. If we assume a depth of 1 m on the reef crest, and using U. S. gallons, this is a flow rate of 2201 gallons/min.

Adjusted to the volume of a 100 gallon aquarium: This is 834 gallons/minute

We would be lucky to recreate this reef crest environment in our tanks. This equals about 50,000 GPH in a 100 gallon tank.

 

[ChrisRD]

Wolfman, I know this doesn't entirely answer your question about how much waste is filtered and how much is simply washed away into the ocean by dilution.

I'm familiar with some of Rob's articles (including these), although it's been a while since I've read some of them - just wondering if there was something specific about how much treatment was happening by each method. I suppose this probably varies greatly from place-to-place and would probably be impossible to study with any degree of certainty. It would be interesting to see a study like that (although I have no idea how it could actually be done). Thanks for the info.

 

[Anonymous]

However, skimming is the REMOVAL of the foam produced by vigorous aeration. I just don't see where it's being removed in the ocean...

This quote and others regarding how the foam is being removed in the ocean. Stop to think about it. It works like this.

There is 12 hours from high tide to high tide. 6 hours the waves are gaining, and 6 hours they are receeding. (A little longer than that since the moon moves, but I'll get to the point)

For the 6 hours, twice a day, (half at night, half in the day) foam is being left on the beaches. The assumption being made by several here is that when the water comes back, it's all washed back into the ocean. This would be true except for one thing. In those 0-12 hours (depending on how high on the beach the foam is left) millions of micro-organisms are feeding off the foam, many of the organisms that only live on the beach to feed off the foam. And of course insects live off the organisms, birds live off the insects, algae grows and feeds on the nutrients, snails live off the algae and lie dormant for a few hours on the beach, etc., etc. The complexity of what is going on is phenomenal.

These organisms are so numerous that most of the nutrients are depleted (or converted to something else) by the time the water returns. This is apparent from a visual look at the beach at different times at the cycle, but a microscopic view would be even more dramatic.

So, in short, skimming does occur in the ocean, but it's more complex than emptying a collection cup into the toilet.

 

[ChrisRD]

Does the sun aid in breaking down these nutrients that are washed ashore (it can be a strong disinfectant)?

 

[Anonymous]

Does the sun aid in breaking down these nutrients that are washed ashore (it can be a strong disinfectant)?

I didn't think about that, but yes, I'm sure it does. Two things at work are UV rays that normally don't penetrate the water more than a foot or so, and for photosynthetic purposes feeding the algae that grows on the rocks on the shore or some plants on the beach.

Lots of seaweed gets thrown onto the shores never to return as well, which can also be a nutrient export.

 

[madrefkepr]

Excellent point!

 

[Garry thomas]

In 1 of my books but i cant remember which one, i think it was in italy, a whole forest was damaged by the froth which blew off the water in a nearby ocean! during a storm. it was either julian sprung, or albert j thiel. Wombat thanks for your interest! The turnover in my tank is 46.660ltr's HR
10.000 odd gallons an hour.

 

[wombat1]

Super Cow, that's a good point. It doesn't just sit there, waiting for the tide to return. However, as you said some of that foam is being converted to something else, whether it's mineralized or incorporated into an animal or plant, rather than being completely removed. The process you described seems not like skimming to me but more like what goes on in a refugium where we harvest xenia, macroalgae, etc (and even remove the occassional cat chasing spiders that are attracted to flies attracted to the light). I understand that some "ocean skimmate" does leave never to return, but I hardly think it compares to the amount leaving our tanks.