UV plumbing with one return line / 2 pumps

[Jasongtr]

I was getting a custom tank but it arrived and was awful quality so ive been refunded, the new tank ive ordered has 2x drains and one return line.

I want to use two pumps still, one smaller one for the uv, and one return pump, ive put some fittings on the bench how i think it would work but wanted experienced reefers thoughts on it, both pumps are dc controlled and have a ball valve and a non return valve then they merge - look ok???

 

[mnl119]

I was getting a custom tank but it arrived and was awful quality so ive been refunded, the new tank ive ordered has 2x drains and one return line.

I want to use two pumps still, one smaller one for the uv, and one return pump, ive put some fittings on the bench how i think it would work but wanted experienced reefers thoughts on it, both pumps are dc controlled and have a ball valve and a non return valve then they merge - look ok???

Why bother with all the complexity? I'm assuming it's an inline UV sterilizer. Just get one bigger pump and go one line through the UV unit. That way no return water can bypass the UV unit.

The only thing I would worry about with your setup is that you have a small pump trying to pump water to the high pressure side of a larger pump and you may get very little flow through the UV unit.

 

[Jasongtr]

Why bother with all the complexity? I'm assuming it's an inline UV sterilizer. Just get one bigger pump and go one line through the UV unit. That way no return water can bypass the UV unit.

The only thing I would worry about with your setup is that you have a small pump trying to pump water to the high pressure side of a larger pump and you may get very little flow through the UV unit.

If you are suggesting one pump and the uv inline then the flow going through the sump as required by the uv flow woukd be too low for the system, thats assuming ive understood you correctly

Or i can use two pumps that are the same so as to balance the flow

 

[mnl119]

If you are suggesting one pump and the uv inline then the flow going through the sump as required by the uv flow woukd be too low for the system, thats assuming ive understood you correctly

Or i can use two pumps that are the same so as to balance the flow

No. What I mean is water is pumped from the sump through the UV then back to the tank. Balancing flow is extremely difficult as you've laid out and you'll never know what flow rates you are getting through each leg of your system since each line will "see" a different back pressure. Also, you'll have significant flow bypassing your UV.

 

[Jasongtr]

No. What I mean is water is pumped from the sump through the UV then back to the tank. Balancing flow is extremely difficult as you've laid out and you'll never know what flow rates you are getting through each leg of your system since each line will "see" a different back pressure. Also, you'll have significant flow bypassing your UV.

I had this idea using one pump

 

[mnl119]

I had this idea using one pump

Again, why bother with the bypass leg around the UV? Ideally you want 100% of the water being returned to the tank to be "treated" by the UV. That way any pathogens in the water are guaranteed to be exposed to UV instead of some bypassing the UV.

I'm guessing that you want to slow down water through the UV thus increasing exposure and radiation dose and that's the purpose of what you are doing here, but you will always have a portion of your return water that's untreated the way you've laid it out. Is my guess correct?

 

[Jasongtr]

Again, why bother with the bypass leg around the UV? Ideally you want 100% of the water being returned to the tank to be "treated" by the UV. That way any pathogens in the water are guaranteed to be exposed to UV instead of some bypassing the UV.

I'm guessing that you want to slow down water through the UV thus increasing exposure and radiation dose and that's the purpose of what you are doing here, but you will always have a portion of your return water that's untreated the way you've laid it out. Is my guess correct?

I cannot just put the uv inline or im only going to get 2× turnover from the return pump

 

[mnl119]

I cannot just put the uv inline or im only going to get 2× turnover from the return pump

Actually, you will get almost exactly the same flow rate back to the tank as with one return line since the back pressure the pump sees will be determined by the single section of pipe going up to the tank and the height differential between the surface of the sump and the surface of the tank (called "head" or vertical lift).

If you look at the graphs on the side of some pumps, it typically shows flow rate versus head height. there is no accounting for return line configuration as it's a minor correction as long as the output diameter of pipe is maintained. I've attached an example.

 

[Jasongtr]

Actually, you will get almost exactly the same flow rate back to the tank as with one return line since the back pressure the pump sees will be determined by the single section of pipe going up to the tank and the height differential between the surface of the sump and the surface of the tank (called "head" or vertical lift).

If you look at the graphs on the side of some pumps, it typically shows flow rate versus head height. there is no accounting for return line configuration as it's a minor correction as long as the output diameter of pipe is maintained. I've attached an example.

No idea what you are going on about but suffice to say my 290 litre system will have a uv that i be running 500 lph through it, if i run just 500 lph back to the tank then im not even hitting 2× turnover

 

[mnl119]

No idea what you are going on about but suffice to say my 290 litre system will have a uv that i be running 500 lph through it, if i run just 500 lph back to the tank then im not even hitting 2× turnove

Buy a bigger pump. It'll probably cost less than the added PVC and valves for your second line.

 

[Jasongtr]

Buy a bigger pump. It'll probably cost less than the added PVC and valves for your second line.

The pump i have does 4000lph but i fail to see why you are not understanding the fact i can only put 500lph yhrough the uv abd you kero saying just run one pump and put it all through the uv

 

[mnl119]

The pump i have does 4000lph but i fail to see why you are not understanding the fact i can only put 500lph yhrough the uv abd you kero saying just run one pump and put it all through the uv

Why can you only put 500 lph through the UV?

 

[Jasongtr]

Why can you only put 500 lph through the UV?

Do you even understand how you use a uv? , it has to flow at a specific rate for the size of the uv or you may as well not bother

 

[mnl119]

Do you even understand how you use a uv? , it has to flow at a specific rate for the size of the uv or you may as well not bother

Don't be insulting. I've set up at least a dozen systems with UV's and have a Ph.D. in nuclear engineering so I understand radiation dosimetry. Bypassing the UV as you've outlined defeats it's purpose. You've bought a UV that's too small for your desired return rate.

As far as flow rate through UV's most are rated for multiple flow rates depending on the desired outcome. Here's an example for the Coralife 12x Turbotwist.

 

[Jasongtr]

Don't be insulting. I've set up at least a dozen systems with UV's and have a Ph.D. in nuclear engineering so I understand radiation dosimetry. Bypassing the UV as you've outlined defeats it's purpose. You've bought a UV that's too small for your desired return rate.

I dont care if you have a phd, im not being insulting i am asking a question if you understand them, you are telling me to pump more through it than the manufacturer recommend and a point ill add ive advised you of more than once, the unit ive bought is already oversized for the tank size i have according to the manufacturer, its clear you have your way so thanks for your advice - no need to continue this now is there

 

[mnl119]

"im not being insulting"

That's for me to judge.

 

[Jasongtr]

That's for me to judge.

Then perhaps run off and lick your over sensitive wounds as i would want to upset the delicate flower you are any more