Rowaphos tumbling

griff500 · May 14, 2018

Just a quick question - when setting the tumbling rate should all of the Rowaphos be moving or just the top layer tumbling?

I can get the top tumbling and looking like the videos with either of the above rates but wondered if there was any difference in effectiveness between having all the Rowaphos moving or the bulk of it not moving and just the top tumbling. I've read people saying both are the most effective and it appears that I can set for the rate faster or slower while still having the top tumbling without throwing everything up high in the reactor.

Maybe it doesn't make a difference but I'd be interested to get any feedback on this.

Hope that makes sense!

GoVols · May 14, 2018

griff500 said:
Just a quick question - when setting the tumbling rate should all of the Rowaphos be moving or just the top layer tumbling?

I can get the top tumbling and looking like the videos with either of the above rates but wondered if there was any difference in effectiveness between having all the Rowaphos moving or the bulk of it not moving and just the top tumbling. I've read people saying both are the most effective and it appears that I can set for the rate faster or slower while still having the top tumbling without throwing everything up high in the reactor.

Maybe it doesn't make a difference but I'd be interested to get any feedback on this.

Hope that makes sense!

Been using Rowa going on three years and love it.

I just dial it into a slow simmer at the top, but not enough to where the fine particles are bouncing around.

Hope that helps and good luck.

Joe Batt · May 15, 2018

Very similar, just a slow boil at the top. The flow meter is reading 97 litres per hour (25.6 gallons for my colonial brothers

)

griff500 · May 15, 2018

Thanks guys.

So, if the majority is not moving but the top is simmering then that's fine - I don't need all of the Rowaphos to be visibly moving?

I want to get the flow rate to be optimal as I never seem to be able to get a zero reading from the output, although that is likely to be down to the amount of phosphate bound in the rock and substrate.

Randy Holmes-Farley · May 15, 2018

It’s not necessary to get a zero reading in the effluent, just a lower reading, [emoji3]

griff500 · May 15, 2018

Ok, but it never seems to be much less and usually not for long, so I still want to get the flow rate correct for maximum efficiency.

So, if the majority is not moving but the top is simmering then that's fine - I don't need all of the Rowaphos to be visibly moving?

Randy Holmes-Farley · May 15, 2018

griff500 said:
Ok, but it never seems to be much less and usually not for long, so I still want to get the flow rate correct for maximum efficiency.

So, if the majority is not moving but the top is simmering then that's fine - I don't need all of the Rowaphos to be visibly moving?

The tumbling degree isn't critical, IMO. I used it mixed in GAC with no tumbling. But I agree a little tumbling on the top is OK, or the whole thing (gently). The goal of the tumbling is to prevent it hardening into a solid brick from precipitation of calcium carbonate, and to prevent channeling.

griff500 · May 15, 2018

Thanks Randy. I can have it so that it is all moving but then it all moves quite quickly, although the top is not moving so much that it throws any fine particles up - it's just moving everything. I can also have it so only the top is moving and all of the top layer appears to be moving around evenly. Either way, the top looks like water on a very low simmer.

I assume that slower flow should remove phosphate more quickly as the contact time is greater, assuming that all of the media is in contact with the water if the majority is not moving. That's why I was wondering if having all of the media moving might be better but then that's offset by less contact time.

I've made it more complicated than it needs to be...

Randy Holmes-Farley · May 15, 2018

griff500 said:
Thanks Randy. I can have it so that it is all moving but then it all moves quite quickly, although the top is not moving so much that it throws any fine particles up - it's just moving everything. I can also have it so only the top is moving and all of the top layer appears to be moving around evenly. Either way, the top looks like water on a very low simmer.

I assume that slower flow should remove phosphate more quickly as the contact time is greater, assuming that all of the media is in contact with the water if the majority is not moving. That's why I was wondering if having all of the media moving might be better but then that's offset by less contact time.

Contact time is complicated.

If you are talking about removing phosphate from the effluent, yes, more contact time in the reactor lowers it more before it leaves.

If you are talking about lowering the tank phosphate level overall, faster flow cannot be worse, unless you are breaking the particles or channeling around them. In this sense, the GFO is always in contact with tank water, and faster flow means less wasted time exposing some of the GFO to lower phosphate water where less binding is expected to take place.