GraffitiSpotCorals February 8, 2012 Share February 8, 2012 Okay so I redid my return lines and put a little bit bigger pump in this weekend. I added three ball valves for supply to gfo carbon and calcium reactor. Also put a 1" on there incase I want to add a fuge or something. I redid my returns so they go under the center brace of the tank where there are no powerheads. I keep getting spurts of air bubbles coming out. I am not seeing any water go under the syphon holes drilled on the returns near the water. I am wondering if there is any other reason that air will randomly get blown out like that? Also air gets in my tlf reactor and I have to shake it out every now and then which is anoying, this was happening even with the maxijet though.. I can plug the holes I drilled with some epoxy but I want to know if there is any other options before I cover them up. I don't need the syphon holes since they are only about a 1/4" above the return outlet. No bubbles make it to the return sump section either. I should probly just plug the syphon holes, thats the only thing I can think of that would make the air come out so random... Link to comment Share on other sites More sharing options...
overklok February 8, 2012 Share February 8, 2012 Your bigger pump maybe cavitating and thus more bubbles!!!!! Link to comment Share on other sites More sharing options...
GraffitiSpotCorals February 8, 2012 Author Share February 8, 2012 Its only 250 odd gph more, I did take it apart and clean it. Its been going on for the past 4 days. I figured if it was something like that it would stop. Should I wait a few days to see if it stops or maybe if I shut down the return whatever bubbles are in it will come up and when I restart it they will be gone? Link to comment Share on other sites More sharing options...
F&Fmgr February 8, 2012 Share February 8, 2012 if your return lines are close to the surface, then the actual water coming out will suck air down with it. does that make sense? Link to comment Share on other sites More sharing options...
GraffitiSpotCorals February 8, 2012 Author Share February 8, 2012 Well I shut down the pump and restarted it. Then I realized there is a clear flex line on top of the pump. No bubbles went through it when they came out the return (at least from what I can see, I will look closer though) so its gotta be coming from something. Also when air gets into the syphon break hole it only shoots out a couple bigger bubbles not a ton of really small ones. I don't know anything about cavitation in pumps so someone can school me. I didn't need to install any check valves or anything to run my reactors off the return right? Also this pump is starting up differently than when it was on my skimmer. I plug it in and it starts then maybe 10 seconds later it gets a big burst and finally starts running full power. I dunno if me cleaning it did something to it or if the fact that its pumping through a 1 inch line and not pumping water through a 6" wide pipe. Link to comment Share on other sites More sharing options...
GraffitiSpotCorals February 8, 2012 Author Share February 8, 2012 if your return lines are close to the surface, then the actual water coming out will suck air down with it. does that make sense? Yea thats what I was figuring it was, but when it does that it only spits out a few and much bigger bubbles, not a ton of tiny micro bubbles. Link to comment Share on other sites More sharing options...
F&Fmgr February 8, 2012 Share February 8, 2012 yeah thats what itll do. sporadically suck larger air bubbles down into the stream of water...does that sound right>? Sean Link to comment Share on other sites More sharing options...
RubberFrog February 8, 2012 Share February 8, 2012 (edited) You have cavitation and it's bad for the impellor blades. Can you plumb in a small line (1/2") to dump some of the return flow back into the sump? Edited February 8, 2012 by RubberFrog Link to comment Share on other sites More sharing options...
GraffitiSpotCorals February 8, 2012 Author Share February 8, 2012 Yea I haven't hooked up my calcium reactor to the third one. So if I hook some hose up to that and let it run for a bit it will get rid of the cavitation? I shut the return down and nothing happened. I held my finger over the only syphon break hole that could be getting air in it and the micro bubbles still shot out randomly so its not that. Link to comment Share on other sites More sharing options...
GraffitiSpotCorals February 8, 2012 Author Share February 8, 2012 Man I just turned off the ball valves to the reactors and pulled the soft tubing off the top of the tlf reactor and it had a ton of pressure on it and poped when I pulled it off. Then the pump then ran half way and then full then half way then full and now its just the return running. I knew adding these ball valves in would be a pain. So how do I fix this? Is the solution just running the third T I have for the calcium reactor back into the sump instead of hooking up the calcium reactor? Link to comment Share on other sites More sharing options...
RubberFrog February 8, 2012 Share February 8, 2012 That's what I would do. You can only throttle down so much. Some pumps are more tolerant than others. It depends on the blade design and the shape of the chamber. Link to comment Share on other sites More sharing options...
GraffitiSpotCorals February 8, 2012 Author Share February 8, 2012 Its a little giant, I never throttled it down though. I did crack the third valve into the sump. I haven't had time to look for bubbles but I will check in a min. Link to comment Share on other sites More sharing options...
RubberFrog February 8, 2012 Share February 8, 2012 By throttling it down, I mean restricting it's output. Link to comment Share on other sites More sharing options...
GraffitiSpotCorals February 9, 2012 Author Share February 9, 2012 I understand, it was wide open all the way up to the returns. The only thing throttled down was the half inch ball valves off the T's but that had no effect on the main line running up to the display, which is only about 5.5 feet. Hopefully tomorow I won't see any bubbles everywhere and your suggestion worked! I still don't fully understand the cavitation idea though. Wouldn't the bubble work itself out eventually? Link to comment Share on other sites More sharing options...
wvreef February 9, 2012 Share February 9, 2012 you are getting air locked inside the line....from the cavation going on as long as that keeps happening you will keep the air bubbles no matter how much you throttle it down....that is why I stayed away from hooking anything to my return lines or intake lines for that reason alone alot of people had problems with it in the beggining and I did not want to fool with getting it just right....you can do it, it will just take some adjusting on your part like stopping the water from sucking air back into the lines.... Link to comment Share on other sites More sharing options...
Marc Weaver February 9, 2012 Share February 9, 2012 If it's an external pump, what size bulkhead are you using for the suction side? If it's 1", I would suggest replacing it with a 1 1/2" bulkhead and reducing the size of the pipe only right at the pump inlet. If you have cavitation you will not see microbubbles in the clear tubing after the discharge of the pump, but they are there. Link to comment Share on other sites More sharing options...
overklok February 9, 2012 Share February 9, 2012 What I do to enable free flow is to route a line back into the sump. For example, I have a return manifold that has three outlets with ball valves attached to each line, two of the lines go to aquariums, one of the lines goes back into the sump. Use large diameter pipe whenever possible. The guy who runs Reeflo told me to have the pipe as large as possible as long as possible. My pipe goes from 2" diameter to 1 1/2' diameter to 1" diameter at the back of the aquarium. Link to comment Share on other sites More sharing options...
overklok February 9, 2012 Share February 9, 2012 A way to tell if your pump is cavitating, is to tap the pump while it is running and see if bubbles start spewing out. If you see a mass of bubbles, you are probably cavitating. Link to comment Share on other sites More sharing options...
Steve175 February 9, 2012 Share February 9, 2012 If you don't have a micro leak introducing micro bubbles via the venturi phenomenon then you have to increase the suction head, or decrease the speed of the pump. As you may know, cavitation happens when the static pressure at the pump inlet minus the equivalent pressure of the fluid velocity in the pump drops low enough to vaporize fluid. To prevent it, the static pressure needs to be higher or the velocity needs to be lower. As a test: try increasing the level of the return portion of the sump to the max level to increase the static pressure head. If this works, it is cavitation and not venturi phenomenon. Link to comment Share on other sites More sharing options...
GraffitiSpotCorals February 9, 2012 Author Share February 9, 2012 Awesome guys, thanks for the help. I am going to tweak it some when I get home. I didn't see any micro bubbles when I went to bed so the routing some flow back to the sump may have worked. I will let you know. You learn something new everyday huh? Link to comment Share on other sites More sharing options...
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