Where to Restrict the Flow?

[aquaventions]

I have a new 100 gallon tank with two 1" drains and one 1" return on a closed loop system. The external Pan World 200PS (high pressure) is rated about 1,750 gph.

I realize the filtration system will slow the flow, but I expect the flow will still exceed my target flow of 1,000 gph.

After the mechanical filters I have a biological filter, a UV (rated for about 1,200 gph), a flow meter, and then the return. I have ball valves before and after the biological filter, and a ball valve between the UV and the flow meter.

Which of the three ball valves do you recommend using to restrict the flow?

 

[dawnmarie]

I don't think it matters which valve you use in this application. If the UV is rated 1200 GPH this is lkely the most you will flow anyway. Curiosity question. Why do you want to restrict the flow ? What is your target of 1000 GPH based on ?

 

[Toby_H]

Most UV manfacturers clearly suggest NOT restricting the flow after their unit... as this increases the pressure within the unit which could result in the unit leaking... So I would ensure the valve between the UV and the flow meter is wide open at all times...


Where is the pump in this set up? I would likely want to restrict the flow immediately after the pump...

Restricting the flow after the mechanical filter will increase pressure in the mechanical filter housing... can this housing safely handle the increased pressure? If so that should be fine...

Restricting the flow after the biological filter will increase pressure in the mechanical filter housing & the biological filter housing... can the housing each of these safely handle the increased pressure? If so that should be fine...


From the description you are offering it seems you are using an overflow (typically meant to be used with a sump) as an intake for a elaborate canister filter... which in my opinion just isn't a good approach... It adds risks/complications but adds little to no benefit (compared to using a conventional canister intake approach).

 

[aquaventions]

The biological filter requires a lot of oxygen given the various bacteria employed. 10x is the optimal flow rate; 6x is the minimum flow rate.

 

[Toby_H]

The biological filter requires a lot of oxygen given the various bacteria employed. 10x is the optimal flow rate; 6x is the minimum flow rate.

I understand/agree that bacteria needs oxygen...

But I do not think I agree with the second half of that statement...


"10 times turnover" is an age old "Rule of thumb" regarding filtration. I feel this is a very good simple suggestion to give to people who are not interested in customizing their filtration...


Bacteria will "remove" (oxidize) waste (ammonia/nitrite) from the water column at an exceptionally wide range of flow rates. And to properly evaluate this situation we must consider the waters "velocity" within the system, not just the "turnover" the filter creates...

 

[aquaventions]

Most UV manfacturers clearly suggest NOT restricting the flow after their unit... as this increases the pressure within the unit which could result in the unit leaking... So I would ensure the valve between the UV and the flow meter is wide open at all times...


Where is the pump in this set up? I would likely want to restrict the flow immediately after the pump...

Restricting the flow after the mechanical filter will increase pressure in the mechanical filter housing... can this housing safely handle the increased pressure? If so that should be fine...

Restricting the flow after the biological filter will increase pressure in the mechanical filter housing & the biological filter housing... can the housing each of these safely handle the increased pressure? If so that should be fine...


From the description you are offering it seems you are using an overflow (typically meant to be used with a sump) as an intake for a elaborate canister filter... which in my opinion just isn't a good approach... It adds risks/complications but adds little to no benefit (compared to using a conventional canister intake approach).

The two drains T into a ball valve followed by two spin-down filters each rated 200 psi. Following this is a ball valve and then the pump. There is a ball valve on the outlet of the pump before proceeding to the 20" mechanical filter rated for 100 psi.

There is a ball valve and the biological canister filter rated for 150 psi.

Between the biological canister and the UV is another ball valve. Between the UV outlet and the flow meter is the final ball valve.

There is no overflow. There are two drains in the bottom of the tank, and a standpipe returning the water to the top of the tank through an elbow directing the flow across the tank waterline; the water exists partially above and partially below the water line.

 

[Toby_H]

Sounds like a pretty nice set up...
　
It's not to often I offer the proverbial thumbs up to inlets or returns in the bottom of a tank... yours is one of them
　
And the multiple ball valves make sense as they allow you to block flow for maintenance/cleaning…
　
　
It seems odd to have the pump inline BEFORE the mechanical media, as this requires solid waste to go through the impeller of the pump… I think I would have tried to put the pump between the mechanical and bio filtration on this set up…
But chances are you considered this and there is a reason you did it this way. I also admit I’m not familiar with the “spin down filters” you mentioned, which may remove the solid waste allowing your mechanical media to serve more as a “fine filtration” chamber…
　
　
But all of that aside, to minimize the resultant backpressure it would create, I would use the ball valve directly after the pump to reduce the pumps output…

 

[aquaventions]

Sounds like a pretty nice set up...
　
It's not to often I offer the proverbial thumbs up to inlets or returns in the bottom of a tank... yours is one of them
　
And the multiple ball valves make sense as they allow you to block flow for maintenance/cleaning…
　
　
It seems odd to have the pump inline BEFORE the mechanical media, as this requires solid waste to go through the impeller of the pump… I think I would have tried to put the pump between the mechanical and bio filtration on this set up…
But chances are you considered this and there is a reason you did it this way. I also admit I’m not familiar with the “spin down filters” you mentioned, which may remove the solid waste allowing your mechanical media to serve more as a “fine filtration” chamber…
　
　
But all of that aside, to minimize the resultant backpressure it would create, I would use the ball valve directly after the pump to reduce the pumps output…

Thank you very much for your thumbs up; this is the first filtration system I've ever planned.

The spin down filters that precede the pump do remove solid waste. Heavier waste falls to the bottom by centrifugal force and then drained via a ball valve at the bottom of the filter. The water then passes through a screen. The second spin down filter contains a finer screen.

 

[aquaventions]

I understand/agree that bacteria needs oxygen...

But I do not think I agree with the second half of that statement...


"10 times turnover" is an age old "Rule of thumb" regarding filtration. I feel this is a very good simple suggestion to give to people who are not interested in customizing their filtration...


Bacteria will "remove" (oxidize) waste (ammonia/nitrite) from the water column at an exceptionally wide range of flow rates. And to properly evaluate this situation we must consider the waters "velocity" within the system, not just the "turnover" the filter creates...

Sorry for the confusion. I was not speaking in general. The specifications of my biological filter call for 10x optimal, 6x minimal turnover rate.