Water not circulating enough

[ToeCutter]

So close and yet so far...

I got everything hooked up and running. I cut up an algae scrubber pad to hold up the media. The media I'm using is crushed coral. The pump I'm using is a Mag3.

With no media, it moved lots of water, no problem. Now, that it's full of media, I can see that the water flows pretty slowly out of the center tube in the reactor.

There's 3 possibilities I can think of - the scrubber is clogging up the works, CC as media is too fine for my setup, or the pump is just too weak.

Any thoughts, Fergy?

Also - I was wondering why you run the water up through the center tube, and down through the media, rather than the reverse direction.

 

[mattboy]

This is something I've been thinking about as well. I was thinking about using a mag 3 (300gph) instead of the eheim (175gph) to increase flow. I'm a little surprised to hear that the mag is not cutting it, although maybe it doesn't handle back pressure very well. I asked Fergy about it; he thought that for the small reactor (12" tube) the eheim would be fine.

This leads to the question about the importance of flow rate and turbulence in reactors. Does more flow result in better dissolving of the media? Is there a point at which there's too much circulation? In particular, I'm wondering if more flow with a given rate of CO2 will drop the ph within the reactor, and if so, is this a desirable thing for our project?

I would try a really loose foam or nylon screen instead of the algae pad, and see what happens. I'm thinking about using some dense foam I have around to support the media, but I've been a little concerned about the same thing; clogging. I'd be interested in what happens when you switch to a more open foam base.

Matt

 

[fergy]

I think that mostly your problems are arising from the fact that MagDrive pumps are total pieces of crap, and overrated. Remember, those things are really just powerheads. Also, they tend to wear out when being used in reactors.

I run the flow the way I do because the media tends to fluidise when run the other direction, creating silt that clouds the tank and never seems to settle out. But, then again, I'm using larger pumps.

The point of using a larger pump is that it seems to mix and dissolve the media better. The goal is that you have enough mixing that the pH in your reactor can be considered to be constant through the entire reactor. If the pump is too low, gradients are set up, reducing the efficiency of the reactor.

BRIAN
_________________
Brazilian Forum

 

[ToeCutter]

I think that mostly your problems are arising from the fact that MagDrive pumps are total pieces of crap, and overrated.

ROFL, ok

 

[fergy]

Honest enough for you? ;-)

BRIAN
_________________
Television discussion

 

[ToeCutter]

I upgraded the pump to an IWAKI MD 20RLT, and the flow is still very slow. It just pours over the center tube a bit. Maybe this is ok... or maybe I still need to change the prefilter or media, or swap out the cobra tubes for larger diameter tubing.

Anyway, the reason I'm posting now, is that I'm wondering if anyone else has theirs up and running, and how fast their water is moving.

 

[mattboy]

Hi Toecutter;

I found these fluval filter pads that seem to be perfect to rest the media on; its the fluval 303, It's a 5 1/2" disc; pretty substantial, but really open foam. I cut one in half like a bagel, so it's about 3/4" thick. Just out of curiosity, why are you using crushed coral instead of ARM? Also, what size reactor did you build?

The iwaki pump has 3/4" i/o, right? I would definitely try bigger tubing.

Matt- STILL waiting on my pump before I can plumb and check for leaks.

 

[ToeCutter]

I used CC because it's cheaper and I heard it's just as good as ARM - maybe not

I built a 16" tube, 22" total height reactor.

Yes - the Iwaki has 3/4 fittings.

Thanks for the tip on fluval, I'll try it if I see it.

 

[mattboy]

I went to a friend's house to check out his Korallin reactor; this is considered to be a decent design, as far as I know, and it uses the same eheim pump (1048) that I'm using. The internal flow in the reactor is real slow; so maybe your flow is sufficient.

Let me know how you're reactor is performing, when you get it running.

Matt