jamesbarr Posted September 18, 2012 Report Share Posted September 18, 2012 hey, so I go a fluval fx5 yesterday from another member. however Its one stock return line is too short to reach my tank top and the intake line is an aftermarket idea that i dont really know where to go with. I was looking to replacement for them online and started to wonder. In the basement of a house I have been working in, I saw a sump pump with the line still above the ground. seems to be the right size. Its been hose clamped to the pump, the same as the line on my filter. Just wondering if anyone has an opinion on using something like this to replace the lines instead of waiting for delivery to use this filter. My tank is under filtered right now and I would really like to get this going asap. Quote Link to comment Share on other sites More sharing options...
jamesbarr Posted September 18, 2012 Author Report Share Posted September 18, 2012 another option is vinyl hose, but im worried about bending it over the top of my tank into the water. will it kink? is there too much pressure from it to use 2 1 inch 90degree fittings to get it over and to my spray bar (yet to be built)? it would be 2 90s to get it over the side of the tank and a 90 to get it hooked to my spray bar. There would also be 2 90s hooked to my intake, Maybe im over thinking this. Quote Link to comment Share on other sites More sharing options...
Jayba Posted September 18, 2012 Report Share Posted September 18, 2012 You could also hard pipe it and ditch the whole hose idea. Quote Link to comment Share on other sites More sharing options...
jvision Posted September 18, 2012 Report Share Posted September 18, 2012 I've done it with PVC - I used 3/4", but I've seen it done with 1" too. There are some good FX5 Mods on MFK and HERE Quote Link to comment Share on other sites More sharing options...
jamesbarr Posted September 18, 2012 Author Report Share Posted September 18, 2012 so i got this thing for cheap so i jumped at the idea. I have a 36gallon tank. am i going to kick my fishes butt with this filter? or will the taps control the flowrate enough? Quote Link to comment Share on other sites More sharing options...
Jayba Posted September 18, 2012 Report Share Posted September 18, 2012 Yes you can control the flow rate with the taps. The water will have longer contact time with the media. All good. Quote Link to comment Share on other sites More sharing options...
jamesbarr Posted September 18, 2012 Author Report Share Posted September 18, 2012 sweet. thanks for the info. some sites are saying that its harder on the pump to have the taps turned back too far, any experiences with this at all? Quote Link to comment Share on other sites More sharing options...
Fisher Posted September 22, 2012 Report Share Posted September 22, 2012 I don't have any experience with the condition, but I understand the theory behind it. Your canister uses an impeller (centrifugal) pump to move water. In industry, impeller pumps can be throttled by varying the impeller rpm. Your canister impeller runs at a fixed rpm. The water that moves through the impeller chamber also cools and lubes the moving parts. If you throttle the suction side too much, your impeller will be subject to hydrodynamic cavitation. The pump isn't able to draw enough water into the pump chamber to keep up with the discharge rate. This creates enough negative pressure at the impeller that air bubbles form and implode on the impeller blades (which makes the sizzling sound, like BBs or marbles). It damages the impeller. When you throttle the discharge, water doesn't move through the impeller chamber as fast, so it 'slips' around the rotating impeller. *Fluid slip creates friction.* All impeller pumps do this anyways. But nominal flow rates prevent fluid slip from being a problem. Quote Link to comment Share on other sites More sharing options...
jvision Posted September 22, 2012 Report Share Posted September 22, 2012 One guy at work literally cooked the pipes (12" PVC) causing them to droop by leaving the valves closed. Remember what Fisher said, the water running thru the impeller chamber cools the system down. When you throttle it back, feel the impeller compartment from time to time to make sure it's not getting warm. If it gets too warm, it could cause the canister to warp. It doesn't matter how good a deal you got on it, if it leaks at the impeller housing and causes your tank to drain and ruins your cabinet and floor, you're gonna be cursing it! Quote Link to comment Share on other sites More sharing options...
Jayba Posted September 22, 2012 Report Share Posted September 22, 2012 (edited) If you need to throttle it back more than a bit heating will become a problem. It is then time for a different route, I'll happily trade you a fluval 305 witth hoses straight across. Another option may be build an output that mimics this thing. http://www.leevalley.com/en/garden/page.aspx?p=62727&cat=2,2280,54307&ap=1 Rainbowric told me about them, and literally a hose full bore and you could then toss it into even a fry tank, disapates the pressure, but not the flow. Edited September 23, 2012 by Jayba Quote Link to comment Share on other sites More sharing options...
Fisher Posted September 23, 2012 Report Share Posted September 23, 2012 Whenever there is an increase in discharge diameter, the result is a pressure and velocity drop. That's what you are doing when you take your thumb off the end of the garden hose. Add more holes in your spray bar, increase the dia of the ones already there, increase the spray bar length and you increase the cumulative discharge diameter. The LV spot soaker (grin) is stuffed with poly mesh to help diffuse the initial discharge inside the ball. Very cool! If the metal makes you skiddish, you could build one out of a fishing bobber. PVC floats for fish netting are available down to 1.5" dia... How ev-ahh: One way to reduce discharge flow into the tank without throttling the discharge out of the impeller chamber is to add a bypass circuit between the discharge and suction lines. Water flows in the direction of least resistance. So a couple Ts, one valve, a foot of hose/pvc... and some clamps, assembled in the right sequence would allow you to lovingly vary the flow to the tank by redirecting some of the flow back to the canister. Maybe another millwright can check mah theory. Quote Link to comment Share on other sites More sharing options...
jamesbarr Posted September 24, 2012 Author Report Share Posted September 24, 2012 (edited) fisher I like your idea. One idea was to run a Y fitting and use 2 spray bars. would that reduce the psi of the discharged water by half? The reason for my thought is that with a Y it would create 3 joints for hose. With the T system there would be 6. With the increased number of joints comes the increased risk of leaks. The other question that i have been meaning to ask is what kind of glue would a person use to connect your pvc pipe? I imagine that you couldnt use the typical solvent glue plumbers use.In the system that jvision links too, buddy uses 2 90degree elbows to bring his intake and discharges over the rim of his tank. I am worried about the pressure hitting the 90degree elbows that hook over the lip of the tank. I realize that the friction fit is pretty tight but the constant pressure on the elbow could push them apart. Edited September 24, 2012 by jamesbarr Quote Link to comment Share on other sites More sharing options...
jvision Posted September 24, 2012 Report Share Posted September 24, 2012 I used PVC glue on all joints outside the tank, and everything in the tank, I didn't even bother. My one FX5 has been running w/o any problems like that for a few years. Quote Link to comment Share on other sites More sharing options...
Fisher Posted September 24, 2012 Report Share Posted September 24, 2012 One idea was to run a Y fitting and use 2 spray bars. would that reduce the psi of the discharged water by half? The reason for my thought is that with a Y it would create 3 joints for hose. The amount of flow resistance in two spray bars with 12 holes each is the same as a single 24" spray bar with 24 holes in it. Agreed, fewer joints makes for stronger construction, always. With the T system there would be 6. With the increased number of joints comes the increased risk of leaks. The T arrangement I described was to put a bypass circuit between the discharge and suction lines, close to the canister. That would bleed some discharge flow back to the canister and reduce the flow to tank. In the system that jvision links too, buddy uses 2 90degree elbows to bring his intake and discharges over the rim of his tank. I am worried about the pressure hitting the 90degree elbows that hook over the lip of the tank. I realize that the friction fit is pretty tight but the constant pressure on the elbow could push them apart. You conclusion is spot on! Any time fluid flow deviates from straight, flow resistance and line pressure increases. Flow resistance, suction or discharge, impacts the impeller chamber. Canister manufacturers design soft "over the rim" transitions for that very reason. Two 90s generate more resistance (and line pressure) than an unkinked hose following a gradual curve. Glue, as jvision already addressed, will keep the joints together. The FX5 User Manual says the stop valve(s) can be used to throttle flow to suit tank needs. With their impeller chamber design, I'm surprised it doesn't say how, or how much. Quote Link to comment Share on other sites More sharing options...
jamesbarr Posted September 29, 2012 Author Report Share Posted September 29, 2012 alas, living in a small town has its perks. Plumbing supply stores isnt one of those perks lol. I thought any hardware store would carry this stuff, but it seems that I will have to drive to the city after all. Blast... Quote Link to comment Share on other sites More sharing options...
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