Return pump flow rate

taki123 · Aug 18, 2022

Hi guys,

I have a Redsea 425XL reef pump with around 300L of water in the tank given a lot of rocks.

I am running a TMC reef Dc return pump 12000L at max flow which I believe is 12000L/h.

This is around 40x the volume of water in my tank per hour. I read online at some places it says run it at 5-10x water volume and others who say the higher the return rate the better.

whate your thoughts on this?
Is there a problem with running it so fast?
Should I slow it down and what’s the benefits of slowing it down to let’s say 3000L/h (10x tank volume)?

Mike konesky · Aug 19, 2022

Anywhere from 2x to 10x imo. Faster can be louder, clear your tank faster if you run a sock, create a more stable temp depending on size of sump/tank. Trident method calls for higher turnover through the refugium. Matching the return to the skimmer has also been recommended in the past. I'm running 2x, 4x, 5x, and 7x on my systems. Curious to know how high people are actually going with turnover.

Jeffcb · Aug 19, 2022

X10 is "standard rule of thumb".

On my 224 gallon I have 2 Cor 20s that should 1500 gallons per hour each at 5 feet head room that should be X13. Ratings are never real. Pumps get dirty, clogged some and slow down with time so its always less than specs.

X40 is a lot but it probably isn't that much.

BaliReefBox · Aug 19, 2022

dont you need a certain amount of dwell time in the sump to allow benificial bacteria to work?

RocketEngineer · Aug 19, 2022

BaliReefBox said:
dont you need a certain amount of dwell time in the sump to allow benificial bacteria to work?

No because it’s not a single pass system, if the ammonia gets through then it just cycles back around later. Same goes for the skimmer, multiple times per day to remove stuff.

taki123 · Aug 19, 2022

So based on your comments seems like there’s nothing wrong with running it faster. I guess my biggest risk is I’m running my pump on max speed so maybe it will give in quicker

RocketEngineer · Aug 19, 2022

If your drain setup can handle full flow of the pump, go for it. If the noise is too much and you need to back it off somewhat, that’s also acceptable. Keep in mind the flow rate listed is with no restriction on the pump. If you account for the ~5’ of vertical head pressure, it’s going to be less. Not all pumps flow the same under load so your miles may vary.

taki123 · Aug 19, 2022

RocketEngineer said:
If your drain setup can handle full flow of the pump, go for it. If the noise is too much and you need to back it off somewhat, that’s also acceptable. Keep in mind the flow rate listed is with no restriction on the pump. If you account for the ~5’ of vertical head pressure, it’s going to be less. Not all pumps flow the same under load so your miles may vary.

Surprisingly the pump is extremely quiet. I’ve seen no ill effects of the pump so far. And you’re right there will certainly be pressure loss so it’s not really at x40. Thanks for your help!

Dburr1014 · Aug 19, 2022

taki123 said:
Hi guys,

I have a Redsea 425XL reef pump with around 300L of water in the tank given a lot of rocks.

I am running a TMC reef Dc return pump 12000L at max flow which I believe is 12000L/h.

This is around 40x the volume of water in my tank per hour. I read online at some places it says run it at 5-10x water volume and others who say the higher the return rate the better.

whate your thoughts on this?
Is there a problem with running it so fast?
Should I slow it down and what’s the benefits of slowing it down to let’s say 3000L/h (10x tank volume)?

I have a refugium and everything runs through it. I do about 3.5 turnover per hour. Refuge is about 5 gallon and the sump itself is a 50 gallon Rubbermaid stock tank holding about 40 gallons. I don't want a high rate though the refuge for contact time.
Most of the flow is at the tank. 75 gallon with 2 wav and 1 mp40.

PeterEde · Oct 15, 2023

Running 4000lph at full speed on my 425 and it's dialed in perfectly. Near zero noise at all. I'm actually amazed at how quiet it is. For now

Reef Puncher · May 3, 2024

taki123 said:
Hi guys,

I have a Redsea 425XL reef pump with around 300L of water in the tank given a lot of rocks.

I am running a TMC reef Dc return pump 12000L at max flow which I believe is 12000L/h.

This is around 40x the volume of water in my tank per hour. I read online at some places it says run it at 5-10x water volume and others who say the higher the return rate the better.

whate your thoughts on this?
Is there a problem with running it so fast?
Should I slow it down and what’s the benefits of slowing it down to let’s say 3000L/h (10x tank volume)?

what i would like to know, is if you have more flow in your tank from wavemakers, does that contribute? for instance. if i had one or no flowmakers, then its crucial to get the flow rate around 5x turnover or more. but if i have a ton of flow in the tank, and its moving water into the overflow because of all the flow, then surely i wont need to have my pump on that high right? you would think this answer would be easy to find, but its NOT

Dburr1014 · May 3, 2024

Reef Puncher said:
what i would like to know, is if you have more flow in your tank from wavemakers, does that contribute? for instance. if i had one or no flowmakers, then its crucial to get the flow rate around 5x turnover or more. but if i have a ton of flow in the tank, and its moving water into the overflow because of all the flow, then surely i wont need to have my pump on that high right? you would think this answer would be easy to find, but its NOT

I'm not sure if numbers have changed but I always have read 3~5x turnover through a sump but 10~+ in the tank for coral.

RocketEngineer · May 3, 2024

Reef Puncher said:
what i would like to know, is if you have more flow in your tank from wavemakers, does that contribute? for instance. if i had one or no flowmakers, then its crucial to get the flow rate around 5x turnover or more. but if i have a ton of flow in the tank, and its moving water into the overflow because of all the flow, then surely i wont need to have my pump on that high right? you would think this answer would be easy to find, but its NOT

The flow in the tank has no impact on the flow through the sump because when the pump is off, the water level in the display drops below the level of the overflow and stops. The little bit from ripples on the surface don’t contribute much to the overall circulation rate through the sump.