Pies Posted July 11, 2005 Report Share Posted July 11, 2005 I have a Deltec AP902. Good skimmer, no real complaints. My question is one governing how best to run it. I have a lot of water flow, so much so I can run more water through the skimmer than it can handle. Currently I am pushing as much water through it as it will take. My question is, whats the best configuration to run it it. Pushing as much water through it as possible? Or less? Is there a way to know whats optimim? You read about terms for skimmers like 'dwell time' etc. So I am not sure. Should I run less water though it and allow it to be skimmed harder, or more water through it, thus skimming more water? Anyone who has any science, links or info i'd like to know a little more than I do. Ta Pies Quote Link to comment Share on other sites More sharing options...
cracker Posted July 11, 2005 Report Share Posted July 11, 2005 I dont think it would actually matter Pie. At the end of the day it is going to clean the water column anyway, Slow or fast shouldnt make a difference in my opinion. As long as the skimmer can handle the litreage. Personally i would try and push as much through it and as fast as you can, ensuring every drop of water is fractionated. Just my little ol' opinion though. Quote Link to comment Share on other sites More sharing options...
chimera Posted July 11, 2005 Report Share Posted July 11, 2005 is there not a suggested flow rate in the user manual?! Quote Link to comment Share on other sites More sharing options...
Ira Posted July 11, 2005 Report Share Posted July 11, 2005 I think the best is the one that gets you the longest contact time, but whether the flow rate is going to have much effect on it? I'm not sure how the water flows in that skimmer. If it's a counter current or what? Quote Link to comment Share on other sites More sharing options...
cracker Posted July 11, 2005 Report Share Posted July 11, 2005 I think pie is saying his total tank turnover is fast. Not that the skimmer isnt contacting the water it is receiving. In other words water is rushing into and out of the skimmer area from the main tank, (Or wherever), and Pie is wondering whether the water is flying past the skimmer and being missed. Is this what you mean Pie? Quote Link to comment Share on other sites More sharing options...
RnB Posted July 11, 2005 Report Share Posted July 11, 2005 this is a great read http://www.hawkfish.org/snailman/skimmer101.htm 1. Water Flow Rate Through the Skimmer: For optimum skimming using a counter current design (or actually any other design for that matter), the water in your tank should not flow through the skimmer any more than two times per day. For venturi's, downdraft's, and beckett's, this requirement is almost a virtual impossibility as the pumps need to pump the huge amounts of water to yield a sufficient quantity of air to skim. This may seem strange and even shocking to many people as they are used to the "Tim Taylor" - type skimmers (more power! Oh Oh OH OH oh!) that push huge volumes of water through a skimmer every hour. Many people believe that to skim more effectively and efficiently, you have to increase the water flow through their skimmer as the air bubbles will contact the air bubbles more times per hour. This is NOT the case. The water running through the skimmer is not the limiting factor when it comes to nutrient export. It's the amount of AIR that contacts each "drop" of water that is the limiting factor to how much a skimmer pulls out of the water column. Some organics require up to 2 full minutes of contact time with air bubbles in a skimmer before they are removed via foam fractioning. Thus the need for a slow wate flow through the skimmer is crutial for proper design and function. According to Escobal, the following chart should be used to determine the flow rate for water through the skimmer (assuming a 2x per day turnover rate): Find the net gallons of water contained in your system on the above chart on the X-Axis and follow that value vertically up the chart until you contact the green line. At that point, follow the line over to the left to the Y-axis. This is the flowrate that should flow through your skimmer for optimum skimming. This particular flow rate will run all of your tank water through the skimmer two times each day. For example, let's say you have 100 gallons of water in your reeftank and you want to find out how many gallons per hour you should flow water through your counter current skimmer for optimum skimming. Find 100 gallons on the X-axis, follow the line on the chart vertically until you hit the green line. Now follow that over to the Y-axis to find out how much water should be run through your skimmer every hour. In this case it is 75 gph. Thus, for your counter current skimmer the tank water should not flow through the skimmer any faster or any slower than 75 gph. Pretty straight forward. Using the above example for a moment, this should then raise another question: I'm flowing 75 gph through my skimmer. According to that, I should be running all of my tank water through the skimmer every 1.333 hours (100 gal/75 gal/hr) and not every 12 hours. Contrary to popular thought, this is not the case. Every time you run water through the skimmer, it dumps the water back into the tank of "unskimmed" water thereby diluting it. As water is continually pulled through the skimmer, it will then pull in "skimmed" and "unskimmed" water. As more "skimmed" water is pumped back into the tank, more and more already "skimmed" water will flow back through the skimmer. According to Escobal, the following equation is used to calculate when 99.99% of the water has flowed through the skimmer: T = 9.2 (G/F) Where T=time, G=total gallons of tank water, and F=flow rate (gph). The 9.2 is a purity coefficient that when used in this equation yields a 99.99% purity. For further explanation of this, please refer to Escobal's book Pies, my opinion is less flow and aim for a wetter skimmate then most people believe is right... like taking a piss... don't wait till its dark, by then you will be dehydrated! Quote Link to comment Share on other sites More sharing options...
cracker Posted July 11, 2005 Report Share Posted July 11, 2005 this is a great read http://www.hawkfish.org/snailman/skimmer101.htm Pies, my opinion is less flow and aim for a wetter skimmate then most people believe is right... like taking a piss... don't wait till its dark, by then you will be dehydrated! The above information would be soley dependant upon the amount of pump pressure in the skimmer or attached to the skimmer....... Its got me buugered, all I mknow is my Deltec pulls out heaps of crap and my turnover is very fast. Quote Link to comment Share on other sites More sharing options...
Pies Posted July 11, 2005 Author Report Share Posted July 11, 2005 What Cracker said is what I mean. My skimmer works fine, but water is ROARING through it, I guess over 5000 litres an hr. So I want to know what is optimal, higher water flow with less contact time (athough it will be contacted more times) or less flow with higer contact time (thus less times through the skimmer). Comprende? I am a retard when it comes to math, anyone able to interpret that article about coefficients and pi squared etc into something I can understand? Pie Quote Link to comment Share on other sites More sharing options...
SteveA Posted July 11, 2005 Report Share Posted July 11, 2005 Why not just reduce the flow going thru it and see what happens? If it is part of your main circulation system and U use this to create current in your tank then compensate by increasing the internal circulation (Tunze thingys). The main reason for taking water out of the tank in the first place (i.e. the whole plumbing system to your basement) is to deliver water to the skimmer, so reducing its speed to test skimming efficiency should not cause any issues. Quote Link to comment Share on other sites More sharing options...
chimera Posted July 11, 2005 Report Share Posted July 11, 2005 I am a retard when it comes to math and spelling lucky you seem to know your sh1t when it comes to reef tanks Quote Link to comment Share on other sites More sharing options...
reef Posted July 11, 2005 Report Share Posted July 11, 2005 Deltec ap902 specs For Aquariums up to: Heavy Stocking 1800 Ltrs (400 gals) Normal Stocking 2500 Ltrs (550 gals) Water Throughput: 3000 Ltr./ h (667 gall/h) 5000L is too much flow, i dont think the skimmer could take that much anyway. slower the water going into the skimmer then you get better skimming, However too slow then you tank does not get skimmed as much. A skimmer should turn over the tank volume at least once per hour Quote Link to comment Share on other sites More sharing options...
Pies Posted July 12, 2005 Author Report Share Posted July 12, 2005 Thanks. Chimera - ? Math is a real word Reef - There is so much water running through it that the water level is at the neck of the skimmer with no restriction. The 32mm output pipe is a solid stream of water and its litrally ROARING out of it its skimming a lot of shite though. Thanks for the Specs, i've seen that before but just wanted to know if there was any science in it. I guess one of the questions is that for 'dwell time'. If the skimmer is running 2500 litres and hr, and the dwell time is 30 seconds, do you get the same/better/worse effect from having 5000 litres and hr with a 15 seconds dwell time. Remember that because twice as much water is passing through the skimmer the overall dwell time remains at 30 seconds (just in 2 passes not one). Am I making sense? SteveA - The return pump that runs the skimmer does provide circulation for the tank, however I have it 'T' off, so it doesn't effect the flow through the tank. Thanks guys Piemania Quote Link to comment Share on other sites More sharing options...
reef Posted July 12, 2005 Report Share Posted July 12, 2005 The water going through the skimmer will not be 5000L it is not possable, i run a ap1004 witha 3000lph pump and the valve is almost fully open, the longer the water in the skimmer the more contact time, so if you put in 2500lph it is going to skim much better than 5000l a lph going in. However if you could attached another needle pump to the skimmer then 5000lph going in would skim as good as 2500lph . Quote Link to comment Share on other sites More sharing options...
Pies Posted July 12, 2005 Author Report Share Posted July 12, 2005 The water going through the skimmer will not be 5000L it is not possable I assure you it is possible I'm doing it. Do you want me to email you a short video of it? I would post it but don't have anywhere that has the disk space. the longer the water in the skimmer the more contact time, so if you put in 2500lph it is going to skim much better than 5000l a lph going in. But given that the water volume is finite, the same water is going to be passing through the skimmer more often. So it will spend the same amount of time in the skimmer, just on multiple passes, not single passes. Right? So if I have 10000 litres of water total. Is it best to pass the 50% of the water through the skimmer every hour (5000 litre hr) or 25% of the water through an hr (2500 litre hr)? If the 2500 25% skims 2x better than at 50% then isn't the net result the same? Pie Quote Link to comment Share on other sites More sharing options...
reef Posted July 12, 2005 Report Share Posted July 12, 2005 I assure you it is possible I'm doing it. If you say so then the skimmer is not working correctly, 3000lph is the correct flow rate. if you put more water in it then it skims less as the contact time is reduce greatly so the water leaving the skimmer is not as clean. Quote Link to comment Share on other sites More sharing options...
Pies Posted July 12, 2005 Author Report Share Posted July 12, 2005 OK I understand that. But if the water is not 'as clean' what about the fact that it passed through the skimmer more often? Does that make up for the fact that the higher water flow makes it less efficient? Pie Quote Link to comment Share on other sites More sharing options...
SteveA Posted July 12, 2005 Report Share Posted July 12, 2005 I assure you it is possible I'm doing it. Pie At some point the skimmer input size is going to act like a tap and restrict the flow. Even if you put a 10,000l/h pump on it you may not be able to get any more thru. You need to line up 25 200L drums and see if you can fill them all in 1 hour from the output of your skimmer. I'll come and watch as an unbiased witness. 8) Quote Link to comment Share on other sites More sharing options...
Pies Posted July 12, 2005 Author Report Share Posted July 12, 2005 An IWAKi 100 can push 10000 litres an hr through a 25mm hole, so no problems there. Anyone is more than welcome to come and witness the through put. In the end its just a peices of plumbing, with a hole in and a hole out, not sure why Reef finds it so hard to belive. Pie Quote Link to comment Share on other sites More sharing options...
reef Posted July 12, 2005 Report Share Posted July 12, 2005 Does that make up for the fact that the higher water flow makes it less efficient? No because you lose the air to water ratio. The ap902 sucks in 1200lph of air, vs 3000lph water flow. So that is a ratio of .4 vs .24 with 5000lph of throughput, So you are losing the efficiency of the skimmer if you put more water in it. That is why when you get a new skimmer it will skim heaps in the first couple of weeks and then slows down as there is less organics to remove. so if you want to skim more you will need a bigger skimmer or maybe get another so you can run both. Quote Link to comment Share on other sites More sharing options...
chimera Posted July 12, 2005 Report Share Posted July 12, 2005 or put a bypass pipe in place Quote Link to comment Share on other sites More sharing options...
reef Posted July 12, 2005 Report Share Posted July 12, 2005 or put a bypass pipe in place i dont think that is the issue as it looks like pies has a bypass pipe on his return. He wants to remove more waste. Quote Link to comment Share on other sites More sharing options...
chimera Posted July 12, 2005 Report Share Posted July 12, 2005 He wants to remove more waste if thats the case, your comments about water/air ratio makes sense. skimmers can only suck in a theoretical maximum of air per hour (and hence how alot of them appear to be rated). if you drive water in faster then the optimal air/water ratio, then you would get fatter (less fine) bubbles thus affecting the skimmers performance. makes sense. get a bigger skimmer!!! if you sell, let me know I'll consider buying yours Quote Link to comment Share on other sites More sharing options...
Pies Posted July 12, 2005 Author Report Share Posted July 12, 2005 Reef - Your right - I want to make sure I am skimming as efficiently as possible. Chimera - I my skimmer is more than large enough for my tank, however if I ever decided I needed to skim more I think I would more likley just add a 2nd skimmer of the same type. - Reef, thats starting to make more sense to me, talking about the air-to-water ratio. Like I said my math ain't good, so i'll have a think on it tonight but maybee thats the key. You can obviously push a lot more than 3000 litres an hr through the skimmer, but perhapps its because of the air/water ratio that sets 3000 as the optimum. I am happy to concede the Deltec have tested it, but I woundered if maybee they said 3000 because its hard to find a way to get more water through it without going into MEGA pump mode. And I just happen to have the MEGA pump. Like I said at the start. Happy with the skimmer, but want it to work as hard as is possible. Churp Pie Quote Link to comment Share on other sites More sharing options...
cracker Posted July 12, 2005 Report Share Posted July 12, 2005 Pie, I think this could easily be taken as a confusing subject. I think Reef is saying your skimmer's pumps, (Which are part of the unit) will pull in 3000 litres per hour into the skimmer. (Deltec would have tested this for sure). Its like trying to put a v8 into a mini. It'll work, but you'll get less life out of your chassis and tyres and so on.... It doesnt matter a rats arse if you had seven Iwakis turning over your tank a million times an hour, The skimmer is still pulling in what IT requires for its design. (3000 LPH) It just means it has more chances to skim the same piece of water than a tank with less TANK flow. (Not to be confused with SKIMMER FLOW). Get me drift? Quote Link to comment Share on other sites More sharing options...
cracker Posted July 12, 2005 Report Share Posted July 12, 2005 As long as your SKIMMER pumps are working to MAX, just leave it! just my opinion. Quote Link to comment Share on other sites More sharing options...
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