hahnmeister
In Memoriam
That is correct, the impellers on MJ pumps are very small and at 18000rpm are plenty 'mixing' for skimmers. I have been using them 'as is' for years on my smaller DIY skimmers.
Reducing cavitation in needlewheel pumps
- Thread starter metalManiac
- Start date
metalManiac
New member
Hi Guys, well because im in Australia i get this info in the morning so i cannot report back when you guys write but here it goes.
I have written this post after i did the modification you said to do. (the one you drew on the next post)
And while the pump does draw sufficient air, i still restrict the ball valve in order to get the pump to draw in even more air (without cavitating the pump).
Randy, as to you second post (the recirc mod), the idea that i had was to actually drill one or two small holes in the plumbing just before the inlet, this way the pump draws water from both the tank and from the skimmer chamber (i think i would haveto be carefull with the hole size because if i drilled a hole too large it would just recirc and not draw any new water from the tank). The reason i wanted to do this is because the ammount of water the pump draws at the moment (and throws through to the frag tank/refugium bit) is ridiculous with microbubbles escaping throughout + it would eliviate the pressure on the pump (from having to draw in the water through the piping).
I really did not want to add another pump (especially in the tank) as this is going as a hang on in the main tank (which is a 2ft).
hahnmeister, yes, what youre saying about the recirc design is what i was thinking!, as for the diffuser or "T", have a look at the pics
. (i did not want to build a diffuser because i have read that diffusiers are inefficient on low diameter skimmers).
As to the type of impeller running on the pump, i have modded the OR clone with the bioball method but have tried and opted for a pondmaster 800L pump with its paddlewheel (no needlewheel mods here). It seemd to be able to handle cavitation better plus the throughput through the skimmer system was better and there are less microbubbles.
I also placed a rough sponge on the outtake baffle of the skimmer (so no microbubbles enter the frag tank) and it raised the water level by 1/2". Im not too fussed as i have plenty of room to work with in terms of the collection cup (the collection cup is a mix of the remora and deltec, with the O-ring idea of adjusting height and the lid of the skimmer taken form the remora and the general look of a slope for a riser taken from the deltec).
Also, i have on purpose placed the holders of the skimmer low so that i do not haveto add another light to the frag tank (i will used the 150W halide thats on the main tank to illuminate the frag tank as well).
And one more final Question, the outtake produces bubles (not microbubbles from the skimmer but its own actual larger bubbles), if i placed a T fitting at the top instead of an elbow (aka durso style) would it help eliminate those bubbles?
Having said that i dont really know how well this thing performs in comparison to other skimmers since this is the 1st real simmer i have ever built. Do you guys think it will be enough to handle a standard 2ft tank with a mixture of SPS, LPS and softies?
(the skimmers chamber dimensions are 4.5" x 5.5" x 20")
As you can see, the background is black and when i turn the pump on and tune it in you can JUST barley make out the background color from the water (it does not look a brilliant white but a tad greyish, keep in mind its only 4.5" wide). The top of the skimmer has no turbulence at all, just microbubbles rising and popping (a large ammount of steam like material comming from this popping).
Again guys, thank you for your help and throught provoking submissions!
I have written this post after i did the modification you said to do. (the one you drew on the next post)
And while the pump does draw sufficient air, i still restrict the ball valve in order to get the pump to draw in even more air (without cavitating the pump).
Randy, as to you second post (the recirc mod), the idea that i had was to actually drill one or two small holes in the plumbing just before the inlet, this way the pump draws water from both the tank and from the skimmer chamber (i think i would haveto be carefull with the hole size because if i drilled a hole too large it would just recirc and not draw any new water from the tank). The reason i wanted to do this is because the ammount of water the pump draws at the moment (and throws through to the frag tank/refugium bit) is ridiculous with microbubbles escaping throughout + it would eliviate the pressure on the pump (from having to draw in the water through the piping).
I really did not want to add another pump (especially in the tank) as this is going as a hang on in the main tank (which is a 2ft).
hahnmeister, yes, what youre saying about the recirc design is what i was thinking!, as for the diffuser or "T", have a look at the pics
. (i did not want to build a diffuser because i have read that diffusiers are inefficient on low diameter skimmers). As to the type of impeller running on the pump, i have modded the OR clone with the bioball method but have tried and opted for a pondmaster 800L pump with its paddlewheel (no needlewheel mods here). It seemd to be able to handle cavitation better plus the throughput through the skimmer system was better and there are less microbubbles.
I also placed a rough sponge on the outtake baffle of the skimmer (so no microbubbles enter the frag tank) and it raised the water level by 1/2". Im not too fussed as i have plenty of room to work with in terms of the collection cup (the collection cup is a mix of the remora and deltec, with the O-ring idea of adjusting height and the lid of the skimmer taken form the remora and the general look of a slope for a riser taken from the deltec).
Also, i have on purpose placed the holders of the skimmer low so that i do not haveto add another light to the frag tank (i will used the 150W halide thats on the main tank to illuminate the frag tank as well).
And one more final Question, the outtake produces bubles (not microbubbles from the skimmer but its own actual larger bubbles), if i placed a T fitting at the top instead of an elbow (aka durso style) would it help eliminate those bubbles?
Having said that i dont really know how well this thing performs in comparison to other skimmers since this is the 1st real simmer i have ever built. Do you guys think it will be enough to handle a standard 2ft tank with a mixture of SPS, LPS and softies?
(the skimmers chamber dimensions are 4.5" x 5.5" x 20")
As you can see, the background is black and when i turn the pump on and tune it in you can JUST barley make out the background color from the water (it does not look a brilliant white but a tad greyish, keep in mind its only 4.5" wide). The top of the skimmer has no turbulence at all, just microbubbles rising and popping (a large ammount of steam like material comming from this popping).
Again guys, thank you for your help and throught provoking submissions!
metalManiac
New member
noone at all has any input?
RandyStacyE
New member
Oh yeah, I bet a T would make a difference. What size output plumbing are you using? Lets just say it's 1". You could use a 1" x 1-1/4" T. It would do even better to help separate the air/water.
