Questions about sump and plumbing

[Tanksy]

Hi all,

 

It's been a couple of years since I tore down my previous reef tank. Life got in the way, moving houses etc.

Now, that we've finally settled down in our home, I'm setting up a new nano reef tank. So excited I'm going to watch again all those little creatures do their thing.
I'm receiving the tank, an Oase Scaperline 60 (60x35x35cm, ~70l) and the cabinet (Fluval Roma 90) in a couple of days and I'm figuring out the plumbing for the sump (40x25x25, ~20l). So I came up with this sketch. Do you guys thing it ticks all the boxes? (Nevermind the baffles in the sump. They're random. I have to figure out that as well)

 

Cheers!

 

 

[seabass]

👍

 

Just a couple of things to consider.  The siphon drain needs a valve; however, a gate valve will give you greater control than a ball valve.  And usually, the emergency drain shouldn't be restricted at all.

 

You can control the return flow with valves if you wish, but I'd be tempted to pick a return pump which provides the flow you want (and not use a valve).  Also, if you wanted to, you could use one return pump and just split the return (assuming that you want two return nozzles).

 

Finally, if possible, I prefer a drilled tank versus a HOB overflow.  A drilled overflow is just more reliable (really no concerns about a broken siphon causing problems).

[Tanksy]

33 minutes ago, seabass said:

👍

 

Just a couple of things to consider.  The siphon drain needs a valve; however, a gate valve will give you greater control than a ball valve.  And usually, the emergency drain shouldn't be restricted at all.

 

You can control the return flow with valves if you wish, but I'd be tempted to pick a return pump which provides the flow you want (and not use a valve).  Also, if you wanted to, you could use one return pump and just split the return (assuming that you want two return nozzles).

 

Finally, if possible, I prefer a drilled tank versus a HOB overflow.  A drilled overflow is just more reliable (really no concerns about a broken siphon causing problems).

Hey seabass,

 

I see your point. I'll replace the siphon drain pipe ball valve with a gate valve.

The rest of the valves are for easier maintenance. I'm going to use 2 DC return pumps for redundancy. Probably 2 Jebao DCP, or DCA, or whatever DC (there are so many different models!) at around 2000 l/h and run them at 50%. The turnover's going to be x5, but I wan't to have the option to increase it if needed. Also, I want the whole system to be as quiet as possible, as it's going to be placed in my office.

My concern is the flow. The overflow weir can handle 2160 l/h. The 1'' drain pipe has a flow rate of 1080 l/h. So, no restrictions there.

I'm not sure the 1/2'' return pipe is enough though. Should I replace it with 3/4'' or it doesn't matter?

Cheers!

[seabass]

51 minutes ago, RookieRock said:

I'm not sure the 1/2'' return pipe is enough though. Should I replace it with 3/4'' or it doesn't matter?

Usually, I'd use whatever size tubing natively connects to the pump's output.  I believe the DCP-2500 has a 3/4" output.  However, I'm almost sure that you could use the 1/2" tubing at that lower setting.

[Tanksy]

15 hours ago, seabass said:

Usually, I'd use whatever size tubing natively connects to the pump's output.  I believe the DCP-2500 has a 3/4" output.  However, I'm almost sure that you could use the 1/2" tubing at that lower setting.

That makes sense.
Regarding the return pump, would 2 Jebao Coral Box DCA 2000 be overkill? Should I go for the DCA 1200 instead?

[seabass]

70 liters * 30 times turnover = 2100 lph (about 555 gph)

70 liters * 35 times turnover = 2450 lph (about 647 gph)

 

19 hours ago, RookieRock said:

The overflow weir can handle 2160 l/h.  The 1'' drain pipe has a flow rate of 1080 l/h

I assume that's with both drains maxed out,  I also assume that you would want the primary drain to handle all of the flow, leaving the secondary drain as an emergency drain.

Therefore, the capacity of the overflow might be considered 1080 lph.

 

What we'd really need to figure is the pump's flow at that particular head pressure.  But assume that you work it out so that your returns are supplying a combined 1000 lph, and you might want at least 2000 lph of total flow in your display, then you might need to add a 1000 lph wavemaker in your display.  A return pump and powerhead in the display would give you redundancy.

 

 

[Tanksy]

28 minutes ago, seabass said:

70 liters * 30 times turnover = 2100 lph (about 555 gph)

70 liters * 35 times turnover = 2450 lph (about 647 gph)

 

I assume that's with both drains maxed out,  I also assume that you would want the primary drain to handle all of the flow, leaving the secondary drain as an emergency drain.

Therefore, the capacity of the overflow might be considered 1080 lph.

 

What we'd really need to figure is the pump's flow at that particular head pressure.  But assume that you work it out so that your returns are supplying a combined 1000 lph, and you might want at least 2000 lph of total flow in your display, then you might need to add a 1000 lph wavemaker in your display.  A return pump and powerhead in the display would give you redundancy.

 

 

Holy smoke!!! Does the turnover really need to be that high? I've read that a turnover of 3-5 times is usually enough. The DT will have powerheads of course, so that I can achieve a flow rate of.... 10x, 20x (?). But a turnover of 30x sounds too much. No? 

[seabass]

Sure, 10 times turnover can work; although I wouldn't go lower than that.  And for a mixed coral reef without SPS, I'd call 20 times total turnover (in the display) more of a minimum recommendation, which is 1400 lph.  But I wouldn't consider 30 times turnover to be crazy high.  A SPS dominant tank can sometimes have well in excess of 50 times turnover.

[Tanksy]

1 hour ago, seabass said:

Sure, 10 times turnover can work; although I wouldn't go lower than that.  And for a mixed coral reef without SPS, I'd call 20 times total turnover (in the display) more of a minimum recommendation, which is 1400 lph.  But I wouldn't consider 30 times turnover to be crazy high.  A SPS dominant tank can sometimes have well in excess of 50 times turnover.

Now you lost me. I've read that the DT turnover and the flow rate are two different things. Turnover is how many times the total water volume of the DT is moved in the system (DT+sump). The flow rate is the total movement of the water in the DT including the return pumps, powerheads, etc. Is that correct?

[seabass]

You can say that I misused the terms if you'd like.  Technically, you might be right about turnover.  I think flow rate has more to do with flow through a pump or through a pipe, but whatever.

 

However, I believe that the flow in the display, and through the sump, should be considered separately.  For example, you might want an hourly flow rate through your sump of 5 times the volume of your sump, and a total hourly flow rate in the display which is 20 times the display tank's volume.  You can see why I just say turnover.

 

So you can size your return pump to provide the proper flow through your sump.  Then take that flow and add it to the flow in your display (shooting for an hourly rate that is 20 to 30 times the volume of your display).  Supplement the display's flow with one or more wavemakers or powerheads to achieve the desired flow.

[Reefkid88]

I would HIGHLY consider using double union check valves as well if you weren't already planning on it. 

[Tanksy]

1 hour ago, seabass said:

You can say that I misused the terms if you'd like.  Technically, you might be right about turnover.  I think flow rate has more to do with flow through a pump or through a pipe, but whatever.

 

However, I believe that the flow in the display, and through the sump, should be considered separately.  For example, you might want an hourly flow rate through your sump of 5 times the volume of your sump, and a total hourly flow rate in the display which is 20 times the display tank's volume.  You can see why I just say turnover.

 

So you can size your return pump to provide the proper flow through your sump.  Then take that flow and add it to the flow in your display (shooting for an hourly rate that is 20 to 30 times the volume of your display).  Supplement the display's flow with one or more wavemakers or powerheads to achieve the desired flow.

Ok, now I got it. I still consider myself a rookie. Thank you for bearing with me.

 

1 hour ago, Reefkid88 said:

I would HIGHLY consider using double union check valves as well if you weren't already planning on it. 

 

I assume you mean I should add one check valve to each return pipe, right?

[seabass]

I was always warned against using check valves.  I forget exactly why... something about having issues if they fail, and that you can setup your sump and plumbing so that they aren't needed.  Anyways, I've never used them.  But I suppose there can be a need for them if your sump cannot handle the volume of back flow when the return pump stops running (power outage, maintenance, etc).

[Tanksy]

I don't know if they're useful or not. I have to look into it a bit more.

 

On another note, I'd like to keep the sump simple, so I was thinking 3 chambers would be enough:

- A chamber for the drain pipes with the mechanical filtration and the skimmer

- A chamber for the refugium

- And lastly, a chamber for the return pumps and the heater.

The ATO will be a different container.

Does that make sense?

[seabass]

Not a big deal; but the only thing that might raise a flag for me is that the chamber with the return pumps is subject to changes in water level.  I know you are planning an ATO, but I still usually put my heater in one of the other sections.  It's your call.

[Reefkid88]

Main thing is,if you are not home and a pump fails,water will stop draining down either line as soon as pressure is lost. So instead of having X amount of water drain into the sump and overflowing it,it stops the water. 

 

 The main issue with them is,gunk building up in the hinges (if a swing check valve) or gunk building up around the ball not creating a good seal and it not working correctly when called to duty. This is why I suggest double union check valves. So you can routinely clean them,preventing them from potentially failing if ever they are needed. 

 

 If you are dumping $1,000-$2,000 into a system by not spend the $20-$30 and have an extra fail safe and just install a full port ball valve before each one so you can shut the valve and clean the check valve once a month or before you leave for a vacay or long weekend. Just seems like a no brainer. 

[Tanksy]

Well, putting it this way it is a no brainer. On the other hand, it's one more part that could fail. 

If I place the outlet nozzles 1/2-1'' below the surface, then the return valves would be redundant, right?

[seabass]

58 minutes ago, RookieRock said:

If I place the outlet nozzles 1/2-1'' below the surface, then the return valves would be redundant, right?

Even with the return nozzles just under the waterline, it's kind of surprising how much water will siphon back into the sump.  However, as long as there is enough space in the sump for this extra volume of water, then check valves really aren't needed.

[Tanksy]

10 hours ago, seabass said:

Even with the return nozzles just under the waterline, it's kind of surprising how much water will siphon back into the sump.  However, as long as there is enough space in the sump for this extra volume of water, then check valves really aren't needed.

Just found out how to calculate that: water level drop (in inches), multiplied by width and length of DT, divided by 231.

In my case 1 inch of water level drop in the DT, is 1,5 gallons in the sump. Let's double that, including the water in the pipes.
So my 6 gallon sump should run half filled under normal conditions, to be able to accommodate all the water returning from the DT in case of a power outage.

 

However, if I drill 1-2 small holes on the outflow nozzle, just below the waterline, I could reduce the amount of water returning to my sump probably by 1/3, right?

[seabass]

4 minutes ago, RookieRock said:

However, if I drill 1-2 small holes on the outflow nozzle, just below the waterline, I could reduce the amount of water returning to my sump probably by 1/3, right?

Remember that the overflow will also drain some water back into the sump.  But yes, if the return nozzles are well below the water line, and the return plumbing sits above them (but is still underwater), then a hole that is higher than the nozzle, but still underwater, would break the siphon sooner.

 

Without a check valve, water will flow back into the sump at a level that is equal to the lowest viable siphon.

 

Also, remember that your skimmer might dictate the water line within your sump.  So there might be a lot of flexibility to lower it more.

[Reefkid88]

Also to,if you are running true loc-line they sell a check valve. 

[Tanksy]

2 hours ago, seabass said:

Remember that the overflow will also drain some water back into the sump.  But yes, if the return nozzles are well below the water line, and the return plumbing sits above them (but is still underwater), then a hole that is higher than the nozzle, but still underwater, would break the siphon sooner.

 

Without a check valve, water will flow back into the sump at a level that is equal to the lowest viable siphon.

 

Also, remember that your skimmer might dictate the water line within your sump.  So there might be a lot of flexibility to lower it more.

Exactly. My design's a mix of the overflow in this video and the Herbie style.

So, the amount of water in the overflow returning to the sump depends on the height of the drain pipe.

 

As for the skimmer, I think I'll go for a Tunze 9001, unless someone recommends a quieter one.

[Tanksy]

I've been doing some calculations. According to these websites...

https://www.copely.com/tools/flow-rate-calculator/ and https://bluerobotics.com/learn/pressure-depth-calculator/

... the flow rate of 3/4'' pipe (SCH 40) at 15cm depth from the waterline (pressure: 0.02 bar) would be 970 l/h. The flow rate of 1'' pipe at the same depth would be 1799 l/h. That is a turnover of 25x the DT, which is acceptable. Does that sound right? 

[seabass]

4 hours ago, RookieRock said:

Does that sound right?

Above is the flow rate at specific head heights (in meters).

 

In addition to the height of the return line, I generally add another foot (1/3 of a meter) for each 90° elbow.  So a DCA200 that's pushing water up about 4 feet with two 90° elbows might not be supplying much flow at all.

[Reefkid88]

This is why even in the plumbing trade (which I work in) I use 2 45's (one regular,one street/spigot) to make a 90 to reduce head pressure on pressurized and gravity systems. More so gravity systems to reduce strain on joints and better flow. 

 

 Shoot,on a refrigerant system you have to add 10ft of line set length for every 90 you use,which is insane and had a operating pressure typicall of 450psi.