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Airstone swims.. Metal in DWC reservoir?

Uncle Eckley

Extreme Member
I've been using these blow-molded conical fermenters as DWC reservoirs to make nute changes quicker and easier. Works great.
 
20210613-161813.jpg

 
The only problem is it's difficult to secure the airstone due to the shape of the walls. The suction cups the airstone provides no doubt work great against a smooth, flat surface like a glass aquarium wall, but they're useless here. 
 
Given the teardrop shape of the thing, I'm sure I could print something to wedge between the smaller diameters above and below the widest section, but I'd prefer not to add some giant contraption for roots to tangle around or that might create stagnant spots.
 
The airstone becomes buoyant when supplied with air pressure and actually flips upside down. I still get enough aeration, but I'd prefer everything in there stay put. So, weight.  I printed this thing, but it's only 45 grams.  Maybe its staying better centered will be enough to stop it swimming around; I need to play with it some and see.
 
20210613-161616.jpg

 
I usually try to stick to glass, rock, and food-safe plastic like this TPU, but I'm thinking a chunk of stainless steel to just nuke this problem from orbit. I feel like that might screw up the chemistry of the solution, but I really have no idea. Anybody know? I don't want to go to the trouble of making the things only to discover they mess with my pH or something. 
 
I really like these stones and mean to stick with them one way or another. Any other ideas as to how I might keep them in place? 
 
Thanks. 
.
 
Hey E!
 
I've never seen an airstone that floats when supplied with air. Seems to me the manufacturer knew about this and supplied them with the suction cups. Is there anything in particular that makes you want to stick with those airstones?
 

Uncle Eckley

Extreme Member
HeatMiser said:
Hey E!
 
I've never seen an airstone that floats when supplied with air. Seems to me the manufacturer knew about this and supplied them with the suction cups. Is there anything in particular that makes you want to stick with those airstones?
 
Dunno, but I'm driving it pretty damn hard. 
 
Circular shape, unidirectional bubble flow. 
 
Uncle_Eccoli said:
 
Dunno, but I'm driving it pretty damn hard. 
 
 
Lol, that's what I thought - hopefully this doesn't put pressure on the pump. Anyway - the way I would tackle this would be as follows:
 
1) Reduce the air flow if your pump has a knob to control it. Probably splitting the line with a 'T' shape connector to another dwc container will work.
2) Get a heavier air stone
3) Get a smaller pump
4) Build a lid with vertical rods that you can snap the air stone to, similar to how you snapped it to the orange base you printed for it.
 
Hopefully this helps.
 

Uncle Eckley

Extreme Member
Siv said:
I've been using this style - seems to be sufficiently weighted to keep it in the right orientation:
 
61OCOMa%2ByOL._AC_SL1001_.jpg
 
I avoided those because they center the air line in the reservoir. The circulation is so strong, though, that the roots get wrapped and tangled with the tubing anyway no matter what I've done, so maybe I will try them now.
 
The orange thing actually works pretty well. I put it into service last night. 
 
Thanks, all!
 
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