Geoff: skimmer design ?'s

[RobinsonFam1]

I have built the Geoff skimmer several times with good success. But heres my new ?.

i am looking to gravity feed the skimmer since i am basement plumbed. I am guessing that i can use the same skimmer design except instead of a pump, just install a pipe with gate/ball valve would to control the flow to the skimmer and the same to control the water height inside the chamber on the output side?

the reason i am asking such a "simple" ? is that i have realized that gravity changes all typical flow characteristics in my situation. I have been having an enormous amount of complications due to a 16' drop to the sump due to flows and pressures and siphons.

let me know what cha think!

thanks!
BR

[wharyat]

If I was to do a gravity feed Geoff skimmer I would use an injector method for creating the bubbles.

Of course the overflow line would have to have a failsafe just in case a snail or something falls down and clogs the venturi or injector nozzle.

Just a few things I was thinking about.

[Geoff]

there are a couple ways of doing this. either air driven, using an air pump and an airstone type bubbler. there are several ultra fine bubble producers made now that should work great for this. i think this is what wharyat is talking about.

the other method is using a recirculating pump to supply the bubbles. for simplicities sake lets use a Mag 7 with a venturi valve. instead of the pump pulling water from a sump it will pull water from the skimmer itself. instead of having 1 inlet and 1 outlet you will have 2 of each. one from the overflow to feed the skimmer new water. one from the Mag to supply the bubbles. one out to the sump, and one out to the Mag. for this i would prolly go with a 6" diameter skimmer to increase the dwell time since the water in there will be moving around pretty quickly. i have a really cool design in my head, but i have to noodle on it for a bit to see if it is truely feasible, but it should work. should not be to much more to build than a normal skimmer. should be under $100 for the PVC anyway.

G~

[RobinsonFam1]

i was thinking the same thing.
I have a mag 5 that i could use too. plenty of PVC since im a builder so that saves more.
i even thought about making some sort of an injector like a penductor (geoff DIY design) and having it shoot through some bio balls before it goes to the body, or a beckett nozzle. similar to the etss evolution 500, while using the mag 5 with a Kent venturi (already have one of those too!) as a re-circ pump and adding more air as well. i think i read that an efficient skimmer is 13% air. thats alotta air!
whatever i do i need to make it happen fast! i can hear my tank critters yelling at me!
since size/height is not a problem do you think that 4" PVC 5' tall would work any better or worse?
i think the biggest hump to get over in this design is the actual size of the body and the height. i believe the rest will fall in place if assembled correctly with the proper intake system.
i wish i had one of those CAD programs for this! maybe i can draw it and take a pic and then send it here.!?!?!?

ohh soo much to lose sleep over tonite.

[RobinsonFam1]

wharyat:
failsafe, i plan on "T"ing off the drain for this. i was thinking the same thing too. that way if something does go in the skimmer feed, my drains can handle the flow with no problems. i will be taking this off the side that has the most pressure also. (dont ask why both drains dont have equal pressure, it was all i could do to keep them 1/2 way quiet, thats a whole other new thread full of flaming and lots of questions from people).

[Geoff]

i also suggest not using any injection method on the drain from the tank. besides what wharyat has suggested there is also the significant lowering of flow that any injection method would cause. a venturi generally adds 7' of head pressure. so you flow from your overflow will be slowed by this much. sorry, do not know how to calculate this, but i am pretty sure it will be significant. this will in turn will require you to valve back your return pump in order to keep the sump from running dry.

having not made a recirculating skimmer yet, i am just winging it here. i would think that the height would need to be double what it is normally to handle the increase in velocity of the water inside the skimmer. not total flow through the skimmer mind you, just the normal flow pluss the recirc flow. this means that you will need a lot more volume to allow the bubbles to evacuate to the top of the skimmer. a 6" skimmer would also accomplish the same thing. i am also thinking about plumbing in an eductor into the 6" skimmer i will be making for the rebuild.

something to consider is doing the triple pass version of the skimmer with a 3" or 4" inner pipe for the second pass. having the air delivery pipe from the pump going through the 6" body and down inside the smaller inner tube. i would use 1" tubing for this feed line. this will give the water plenty of time to slow down. the pull from the skimmer to the Mag, i would put about half way up the skimmer body, this will also help keep the velocity in the lower part of the skimmer down, hopefully keeping the amount of bubbles escaping in to the sump to a minimum. as for the inlet from the overflow, i would put this about a quarter of the way down the skimmer body. the outlet into the sump should be as low to the skimmer bottom as possible.

i want to see pics.

G~

[RobinsonFam1]

pics will be here soon enough. hopefully i can start this monster thing on saturday. along with everything else to do on saturday including janitor shopping.......

im not too worried about sump running dry since this will be "T"d off the drain instead of 100% drain flow. i have a valve on the drain line in case i do need to throttle it back but i think it will be fine. i will cheat and make the Tfrom 1.5" pipe and then reduce it to 1" as it goes into skimmer, this will allow me the most flow and pressure as well.
ok...so heres the plan....
5' tall....the overflow feed line will just come into the body about 18" below the neck.....the mag 5 will either be an enductor shooting down the inner 2" pipe about 2' off base, OR use the Kent venturi in the same manner, or maybe even both (that might require some bathtub testing to do both).......the exit to sump pipe is the easy one. about 3/4" off the base elbowed down, on the outside i will bring it up almost 3' (or more) then dump into the sump, this will be controlled by a valve to adjust skimate. i will build some sort of bracket or shelf for the mag to stay as close to the body as possible to minimize head pressure on it and get max flow.

im trying to figure out how to plumb in an eductor to get thee right flow/air combination.......

since this is pure prototype i plan on cutting a few corners and trying some cheap routes. if it works then great, or needs tweeking then im not too far in the $$$ hole.
i also have plan B on backup using a small plastic "barrel" derived from the "EAP euro" thread on RC.

at any rate i do plan on making a re-circ style to maximize efficiency.

1 day left for anyone with some last thoughts! lemme hear em all!

[Geoff]

when Teeing the drain water will take the easiest route. more will go out the non skimmer end than the skimmer end. i would just run the entire drain into the skimmer full bore. what is your return pump? how many gph is it pumping, approximately? make the skimmer outlet at least a 1.5" outlet.

for the eductor. do you know how they work? you will not be able to run both a venturi and an eductor in line. pressures will be fighting eachother. i have not had a chance to raid the plumbing aisle so giving you exact plans is tough. i do think that a 1.5" tee would be a good housing for 1" DIY eductor. when using an eductor it must be higher than the resting water level of the sump. it is also a good idea to run the air feed tube higher than the skimmer so that if a power outage does happen, as the water surges into the sump it does not take a short cup out of the eductor air feed tube, leaving a mess on the floor.

Galleon had a great eductor skimmer plan on here. but the pics were lost during an earlier server upgrade. i think the parts list is still on the thread though, so you can use that as a start. do a search in the DIY archive for eductor skimmer. it should find it.

G~

[RobinsonFam1]

ill do that search!

my flow is pretty high! im running a hammerhead as a return. going by the charts i should have in the vicinity of 3800 GPH. it comes back down
2) 1.5" drains. one drain has a durso and the other is a half baked style of the stockman skimmer drain that i kinda had to re-create myself to fit/work with my system. doing this combination of drains was the only way i could quiet things down. the drains do not have equal flow either to really confuse things. im guessing the 2000+ GPH comes down the stockman side. this much flow is what makes me want to go with such a tall skimmer to increase contact time.

ok, will try 1.5" on the skimmer outlet.

im pretty sure of the eductor but am still reading about them as to how to make them best suited for this idea. im thinking the eductor to be up high on the skimmer body. kinda like most beckett designs are.

no, i wasnt planning on running the venturi and eductor in the same line. i do realize that wouldnt work for a hoot. i was planning on making the eductor as part of the drain line feeding the skimmer. and then with the mag as a recirc pump, adding the venturi on that to add more air if needed.

i have decided to push this assembly back till later this week. things are getting pretty hectic around the house right now.

[RobinsonFam1]

ok...i found his thread after going to the memberlist.

it is essentially the same thign i was thinking of building. there are a couple of pics left but none of his originals. i think i can wing it from here though.

so the base of the injector should be at the same level as the water in the body? im thinking if i can get his assembled right it will be a kick a** skimmer for next to nothing in cost and $0 to run!!!

ill see if i can get some sort of drawing on here this weekend.

BR