VCA random flow generator

[canadianeh]

So I have this installed in the tank. I understand that return nozzle needs to be close to surface to avoid siphon effect of the power is out?

The issue is this VCA nozzle suck in air and create bubble when it placed near the surface. Anyone has this issue?

 

[Crustaceon]

Place it low enough so that it doesn’t cause a whirlpool at the surface but isn’t so low that it siphons enough water to overflow the sump. I have dual loclined returns set up this way.

 

[hyprc]

Extremely commonly mentioned issue on this forum and others. You can drill a hole at a high point in the return to break the siphon (beware of salt creep sealing it back up) and be able to keep it low enough to where you don't flood your sump in a power outage.

 

[Phil D.]

Actually, if you look at the rear of the nozzle, you will see open ports. These will break any siphon no matter what level you have nozzle at.

 

[canadianeh]

Actually, if you look at the rear of the nozzle, you will see open ports. These will break any siphon no matter what level you have nozzle at.

Really? I have to check it out. Do you have the same VCA nozzles and set them not close to the surface?

I am thinking. We should be able to direct this "loc lines" type of nozzles where we want as they are designed to be flexible and can be directed to any direction. If we have to keep it on the surface then we should just stay with the stock nozzle. If there is no "siphon break" feature then to me it is a design flaw on these type of nozzles.

 

[canadianeh]

added @Vivid Creative Aquatics

 

[Phil D.]

I do have these nozzles on my Red Sea E-260. I have them set 1/2 first finger length below surface and when I put my return pump into feed mode and turn off circulation pumps, they don't siphon the water below them.

 

[Larry L]

Make sure you position the nozzle according to their guidelines: https://vividcreativeaquatics.com/wp-content/uploads/2019/03/RFG-Installation-Guidlines-1.jpg

 

[canadianeh]

Can one nozzle go really deep and the other close to the surface (following the guideline)? Will I still have siphon break if only one of the nozzles close to the surface?

 

[Red_Beard]

Can one nozzle go really deep and the other close to the surface (following the guideline)? Will I still have siphon break if only one of the nozzles close to the surface?

Yes, I have 2 1/2 returns and that is how i have mine set up.

 

[Vivid Creative Aquatics Verified Sponsor]

added @Vivid Creative Aquatics

Thank for the add

Make sure you position the nozzle according to their guidelines: https://vividcreativeaquatics.com/wp-content/uploads/2019/03/RFG-Installation-Guidlines-1.jpg

Yep - that's the right set of instruction

@canadianeh - here is the quick start guide to get the RFG nozzle as close ot the surface as possible

Your idea of place one nozzle deep and the other more shallow would work in terms of causing a siphon break. This is assuming both nozzles are being feed from the same supply line, the siphon will break at the point of the highest inlet.

If you can give me a few bits of information about your system, i can run a few calcualtions and give you soem guidance as to how deep the RFGs can be.

I just need:

• the overall dimensions of your display tank
• The overall dimension of your sump
• The average water height of your sump (just split the different between the high point and the low point)
  
  
  
  
  

 

[canadianeh]

Thank for the add




Yep - that's the right set of instruction

@canadianeh - here is the quick start guide to get the RFG nozzle as close ot the surface as possible

Your idea of place one nozzle deep and the other more shallow would work in terms of causing a siphon break. This is assuming both nozzles are being feed from the same supply line, the siphon will break at the point of the highest inlet.

If you can give me a few bits of information about your system, i can run a few calcualtions and give you soem guidance as to how deep the RFGs can be.

I just need:

• the overall dimensions of your display tank
• The overall dimension of your sump
• The average water height of your sump (just split the different between the high point and the low point)
  
  
  
  

Hi there, please see my respond below.

• the overall dimensions of your display tank 36" L x 21" x 20" W (54 gallon display tank volume)
• The overall dimension of your sump 11 gallon of sump volume
• The average water height of your sump (just split the different between the high point and the low point) about 8"-8.5"

 

[Vivid Creative Aquatics Verified Sponsor]

Hi there, please see my respond below.

• the overall dimensions of your display tank 36" L x 21" x 20" W (54 gallon display tank volume)
• The overall dimension of your sump 11 gallon of sump volume
• The average water height of your sump (just split the different between the high point and the low point) about 8"-8.5"

Thank you - here's what i have calculated

Display Tank
Aprox 3.25 Gallon per In of water height using the following calculation

Length * Depth / 231 = gallons per inch of water height
36*21/ 231 = 3.27 Gallons

Sump
I guessed on your overall sump dimensions base on your total volume of 11 gallons. So, I use 20" x 12" x 10" as an overall sump dimension for the calculation. Your sump holds approx 1 gallon per inch of height.
20 * 12 / 231 = 1.03 Gallons


Based on a 12in sump height , with a 8.5in average water lavel you have an estimated 3.5in of reserve space in your sump.

3.5 * 1.03 = 3.6 Gallons of reserve space

Results
Since you have an estiamted 3.6 Gallons of reserve in your sump, and your Display tank holds approx 3.25 gallons of water per inch of water height, I think you could safely have the RFG nozzles sit at 1in below the water line.

Of course you'll want to test these numbers while standing in front of the tank. Simply place the nozzle about an inch below the water line - follow the instruction in the Quick Stat guide to position the RFGs, and then turn off the return pump to simulate a power cut. Monitor what happens and adjust as needed.

Hope that helps and it not too confusing.

 

[ca1ore]

Can one nozzle go really deep and the other close to the surface (following the guideline)? Will I still have siphon break if only one of the nozzles close to the surface?

That's risky. There was somebody here who did that and still got a siphon from the lower nozzle. I think you test it before assuming it will (or won't) work.

I use a pair on my closed loop where I don't need to worry about siphoning and they work really well. Not personally a fan of them on the main return though.

 

[canadianeh]

Thank you - here's what i have calculated

Display Tank
Aprox 3.25 Gallon per In of water height using the following calculation

Length * Depth / 231 = gallons per inch of water height
36*21/ 231 = 3.27 Gallons

Sump
I guessed on your overall sump dimensions base on your total volume of 11 gallons. So, I use 20" x 12" x 10" as an overall sump dimension for the calculation. Your sump holds approx 1 gallon per inch of height.
20 * 12 / 231 = 1.03 Gallons


Based on a 12in sump height , with a 8.5in average water lavel you have an estimated 3.5in of reserve space in your sump.

3.5 * 1.03 = 3.6 Gallons of reserve space

Results
Since you have an estiamted 3.6 Gallons of reserve in your sump, and your Display tank holds approx 3.25 gallons of water per inch of water height, I think you could safely have the RFG nozzles sit at 1in below the water line.

Of course you'll want to test these numbers while standing in front of the tank. Simply place the nozzle about an inch below the water line - follow the instruction in the Quick Stat guide to position the RFGs, and then turn off the return pump to simulate a power cut. Monitor what happens and adjust as needed.

Hope that helps and it not too confusing.

Actually my sump dimensions are 16.5” W 13.5” H 18.5L

 

[Vivid Creative Aquatics Verified Sponsor]

Actually my sump dimensions are 16.5” W 13.5” H 18.5L

Even better - that puts you total sump volume at more like 17 gallons

Revising the estimate sump reserve space you have

You sump hold approx 1.3 gallons per inch of height
16.5"W * 18.5"L / 231 = 1.32

if you your average water height in you sump is about 8.5", then you have an average of 5in of reserve space in your sump, which equals about 6.5 gallons of reserve space

5 * 1.32 = 6.6 Gallons of reserve space

that would give you enough reserve space in the sump to safely have the nozzle 1.5 to 1.75" below the water line

Again, test this while standing next to the tank, just in case the estimates are off. ;-)