Skimming conversation

[moonpod]

It terms of "do I have enough skimmer", it's a subjective question. Objectively if your system is healthy (fish fat and happy, corals growing with good color etc...) then beyond that I have very little else objective data for someone to reliably use. That being said, I am a believer in heavy skimming. I personally think it's difficult to "overskim" a system.

I have a Deltec AP702. I run it dry actually, though I'm still playing around with it. this is a recent change from a GEO 8x36" dual sedra 5000 recirc. The Deltec is skimming circles around the GEO, BUT it is a larger unit and SHOULD skim circles around it. I have a very heavily fed 180g FOWLR.

 

[thetedinator]

ASM G2 with Sedra 3500 - Dry Foam

 

[OUinLA]

right now i'm using a Southbay 6-1 with a sedra 3500? (after the comparison I will use the Bubble King 250) Wet foam always. I've never understood the dry foam thing. We always talk about trying to get the bigger or best skimmer, but then people want dry foam with it. Doesn't make sense. If you want your skimmer to remove nutrients from the tank then you should be running it on the wet side. The downside is you remove a little salt water.

For me I know the skimmer is the right size for my tank when it stops skimming. If the skimmer is always pulling something out then it may not be removing everything as fast as it's being introduced. I try and skim very aggresive to the point where it doesn't produce very much except right after feedings, blowing off the live rock, etc.

 

[spooda420]

Aqua C EV400 powered by and Iwaki 55rlt ... very dry foam.

It pulls out about 3 gallons of skimmate a month. The kind that looks like strong coffee, it just does not smell as good.

 

[sberman]

i am running a mtc 1000 on a very heavy loaded sps tank with lots of fish and lots of feeding i get about 5 gallons of simi wet skimmate a week out of it the mtc is easy to adjust and once adjusted u leave it alone i clean it every four weeks takes about an hour the skimmate goes to a five gallon bucket that i empty and replace

 

[NaH2O]

sberman - Welcome to Reef Frontiers!!!

Just some additional info to add to the thread. Here is an article on SKiming BAsics 101: Understanding Your Skimmer. The article shows how skimmers work, as well as pictures of the different types of skimmers out there. May help to have some visuals (I always do better with pictures).

Wet or Dry Skimmer Foam?

Wet vs. Dry Skimmate

I like my skimmate wet, and it pulls solids out, too. If I do a big tank clean, there will be some algae that makes its way into the cup.

I clean out my skimmer cup every 3 days or so....and clean the skimmer neck, too. Isn't a clean skimmer important, as the surface stays smooth for the bubbles to travel up? When mike/mojo made the wet neck on his skimmer....it enhanced skimmate production, and Deltec has the brush that cleans the neck once a day (I think??). So, how often should we clean the skimmer itself - does it really make that much of a difference?

Another question I have.....taller or wider - which is better? Does it depend on skimmer type?

 

[ereefic]

MR-1 with Gen-X 6500 Pump - BB and skims wet

MR-2 with Gen-X 8500 Pump - DSB and skims a little drier

 

[cheeks69]

Thier are folks that dont believe in skimmers at all, others like me that believe the more the better. For me skimming is the back bone of my filtration system, so i rely on it for removing not only disolved but also particulate matter

Protein Skimming: How It Works

Mike don't you use filter socks in your system ? I use one and it removes the particulate matter so I'm left with mostly dissolved so I guess I should try to get a dry skimmate :?:

Here's my modest Turbo-flotor multi

 

[mojoreef]

Robert I only use the socks for about a day once every two weeks or when the detritus in the water column has to much in it.

Mike

 

[cheeks69]

Oh ok :exclaim: I use mine every day it keeps the water sooo crystal clear and when it gets dirty I just put another one, it also clears my micro bubble problem, I'm just too lazy to find the problem :lol:

 

[ldrhawke]

Wet or Dry?

Wet or Dry Foam?

It would be interesting to see an actual lab analysis as to exactly what ends up in the skimmer cup for both approaches. It would require measuring both the dry weight of the residue as well as the total organic volatile content. I personally believe a wetter skimmate is better, but I do not have data to prove this.

My thinking is based on my belief that if you try to keep the skimmate too dry, you maybe allowing too much of the finer waste particles and volatiles to be recycle back into the tank.

Allow me make an analogy that is part of the basis for my thinking this way. In commercial waste water treatment, various types of biosolids(sludge) removal equipment, centrifuges, beltfilters, vacuum filters, etc; are used to remove solids from the processing tanks. The best performance is not based simply on the driest waste produced.

In evaluating the performance of dewatering equipment, dry sludge cake is important, but not the only criteria. As important is capturing as much of the very fine material in the waste stream. If you do not, it will eventually over load the wet end of a waste water treatment plant. Wet or dry skimmate may also be one of the big differences between a successful reef tank and one that fails.

In dewater sludge in a waste water treatment plant, it is relatively easy to get a dry sludge cake. ie, dark skimmate-dry foam. You can do this by scalping the waste stream and only removing the largest and easiest to capture particles. The problem is that when scalping, you are often only capturing 80 or 90% of the solids passing through the filter and you are allowing the finer material to be recycled back into the plant to be reprocessed. These fines can virtually over load a waste treatment plant within a few weeks because they still contain a very high biological oxygen demand (BOD) material. When the dewatering equipment is adjusted to capture these fines and recover 98% of the fines, it produces a much wetter sludge which has a lot more water weight.

I believe if better testing is done for skimmers, some of this analogy will apply to a reef tank skimmer also. A wetter skimmate is removing lot more water in the dark tea color skimmate, but I believe you may may find that you are also removing more of the fine material and higher organic volatile material. When you adjust the skimmer for a very dry foam and adjust to obtain the darkest driest skimmate, alot of the fines may be recycled.

This is only my opinion. Several reefers that have bare bottom tanks have stated they cannot keep nitrates down unless they run with a wet skimmate, which sort of supports my opinion. Testing for the total amount of organic waste and volatiles removed for dry and wet skimmate would be a good performance and lab test to run in evaluating skimmer performance. I don't believe the present testing visual methods being used for skimmers will prove every much.

Also, when removing a wetter skimmate, you do have to adjust for the drop in S.G. by adding more fresh salt mix. I view that as a good thing because you are also adding back in trace elements that are being removed by skimming.

 

[DLONG]

I have one of the first ETS downdraft skimmers (model 1000 now I believe) on the West Coast that I purchased in about 1995 (if I remember). It was kick *utt when I first got it; then it became "dated" as the years went by.
I removed the jet nozzle and replaced it with a beckett and now it runs great. Use a Iwaki 70 on it. I wonder how it would compare to the Barr Aquatics sk4200 ? Really interested in that one.

 

[Scooterman]

Well my no..2 cents here, I have a turbo floater 1000 sump model.
I don't have much to clean asides the cup, it looks as nasty as the posted pick above. I end up cleaning it about twice a year, I'll take it apart and soak it in vinegar a few hours then soak wash with dish washing liquid & then rinse, and rinse & rinse. It never really drops off in skimmate, I empty the cup about twice a week, fairly wet. Like Nikki mentioned, when the cup get full of slimy crud it does seem to slow production down but that usually occurs when it needs to be emptied anyways. Now this skimmer produces micro bubbles, probably finer that the average skimmer from what I read but hard for me to give an honest comparison so I'll leave it at that. I wonder, if I could get a better skimmer if it would actually pull even more gunk out quicker, better etc. is it worth trying to get or make an even more efficient skimmer? Sometime I wonder if I installer two skimmers side by side what would happen. I only have a 100g tank so comparison to larger tanks, I may not need to worry about trying to get more than I'm already getting, I don't keep a heavy bio-load anyways.

 

[Zephrant]

The size of the reaction chamber, air intake, and the # of seconds that the water says in the skimmer are all critical to the amount of foam a skimmer can generate. I'd like to see skimmers rated in # of seconds that it takes for 1 gallon of water to pass though the system (average) and the amount of air (SCFH) that gets injected in that time. That could give us another way to analyze performance, that is all mathematical based.

Consider a skimmer that runs the water though in 8 seconds, vs one that takes 24 seconds. If they both run the same GPH, and even the same air intake one could claim that they would perform similarly. But I would expect the performance of the second one to be much better as the bombardment rate would be higher.

So how do we get longer contact time? Size matters. Wider, taller, convoluted paths like the old counter-current air-stone skimmers, all of these things can add contact time. This need to be coupled with a good air-intake device (Beckett, venturi on a needle-wheel, etc) of course.

I know of several companies that are coming out with bigger chambers- even up to 16" I've heard. I suspect there is a point of diminishing returns. For systems 500g and less, the existing skimmer are great. I feel there is room for improvement for larger systems though.


Dlong- The ETS skimmers that I've seen are built great. When I got serious about making skimmers, I studied the ETS the most. They use thick flanges everywhere, counter-sink all tube grooves, and are just a quality product. If you did your Beckett improvement with an air-tight chamber for the Beckett and an air valve, then you should be getting most of the performance that you would see in a SK4200, or other similar Beckett skimmer. The only reason left to upgrade is if you wanted a bigger chamber, longer contact time, or just liked the features on newer skimmers.

As mentioned before, the main downside to Becketts are the large pumps needed to drive them. Buying a big Beckett and driving it with a power-head should be a crime.

Zeph

 

[DLONG]

Zeph, thanks
"The only reason left to upgrade is if you wanted a bigger chamber, longer contact time, or just liked the features on newer skimmers."

That's what I figured. The bigger chamber might help, and the newer designs are easier to clean. Probably need a newer calcium reactor before skimmer. My reactor is nuts to change media in.

Not to change topics, but........Zeph, do you ever get to the Seattle area? I have an overflow box problem that I NEED someone to help me figure out. The maker of my tank made it so the the overflow "leaks" and therefore drops a couple inches when the power is out. This would be ok, except many corals are at or even out of the water surface BEFORE the power goes out. The tops of my corals die when I lose power (even with a generator). Been this way for years, but now I am tired of killing the tops of my corals every so often. I can't figure out how to fix the problem without much down time. I was thinking the maker of overflow boxes could come up with ideas that I can't.

 

[mojoreef]

ldrhawke good to see you over here at Reef Frontiers, Welcome aboard!! How is that plenum wasteing going?? I havent had a chance to read on it in a few months??

Brent good post, those are some of the things that I think are critical to. As mentioned by both you and ldrhawke contact time, bubble size and cfm entering the water are pretty much the basis for which we can look at a skimmers importance. Neddle wheels from my research (not much) run at about 1 cfm at best. Do you have any info on beckett or venturi??
Personally I cant see them being much more then that with out the pump crapping out from to much air. I am really starting to wonder back to the old days and airstone driven skimmers. You cant beat them for contact time, you cant beat them for bubble size, you can put a hell of a lot of cfm through them. I was talking to a friend in the aquaculture biz, on the equipment set up side and he was saying that the tech of the diffusors and air pumps have take leaps and bounds because of the lake and pond reclimation going on in the US.

Might be time to give that another shot.


MIke

 

[mojoreef]

Oh Delong I ran the etss 1500 for years, great skimmer.


Mike

 

[Zephrant]

Here is a chart I made a while ago- I hooked up a Becket in an air-tight chamber, with a 3/8" ball valve on it and ran it in to a Bucket. Powered by a Sequence 3600, which is why it maxed out at about 625 gph. I need to repeat the test with a bigger pump. I used a ball valve to cut down the water flow, and measured the air for each point. Notice the sharp roll off around 350 gph. At 300 gph I could not even get a reading on the meter.

Also notice the big jump between 500gph and 600gph. Almost double the air injected for a 20% increase in water flow.

I ran the end points, and middle point tests twice, hence the double data points. I used a 0-50 SCFH meter for the low points, and a 0-300 meter for the higher points.

Zeph

 

[mojoreef]

Excellent Brent! exactly what I was looking for. I have to admit a little surprising though, I would have expected more cfh or cfm.


MIke

 

[ldrhawke]

I used a ball valve to cut down the water flow, and measured the air for each point. Notice the sharp roll off around 350 gph. At 300 gph I could not even get a reading on the meter.

Also notice the big jump between 500gph and 600gph. Almost double the air injected for a 20% increase in water flow.

Zeph

I see youy used a Dwyer type meter to measure air flow rates. What did you use to measure the water flow rates?

ldrhawke