Plumbing

Jivatma · Jun 7, 2021

I'm building my first tank and so I'm still in the planning stages, so do please, share away! I'd rather get it right the first time than not! I don't want to run the risk of over the edge overflows, so I will be drilling my tank. I also figured if I was going to avoid HoB overflows, why not drill for return lines as well!

75g DT
40b sump
Varios-2 return pump (3/4" return lines)
EMS 32" overflow (1" drain lines)

So I have a few questions,

1) Do i still need a way to stop backflow in case of power outages? If thats the case, should my return lines be drilled near the waterline? I know reefers have a mixed review on check valves, and I can see both sides of the argument there.

2) Are there locline alternatives? This is just a personal preference, but I don't much enjoy the way locline looks. This is just a cosmetic thing to me. I have entertained the idea of something like a jacuzzi/spa outlet that is more flush with the back glass, but I haven't seen it done before.

3) How many return lines? At first, I wanted two, but then I thought one might be better, but now I'm flip flopping on which I should do. With the 32" overflow, I'm kind of limiting myself space for return holes.

DCR · Jun 7, 2021

You can install a check valve, but I would not depend on it to prevent an overflow. Your sump needs to hold the drain down volume. Keep in mind that unless you provide a siphon breaker hole near the surface, it will drain down to the exit depth of the Locline

I used a spa type return bulkhead back in the 80's for limited directional control. Now I prefer to just return through an open bulkhead and create the internal flow with powerheads. All you are doing with these exit nozzles is providing some directional flexibility and trading a reduced flow for an increased exit velocity. If I used a Locline I would not use the flared end pieces. The end pieces will reduce your flow rate considerably.

You are probably looking at 250-350 gph at 100% on that pump depending on the plumbing and if you put Loclines on it. Two 3/4" returns would be OK, but if you go with one return I would increase it to 1" to take advantage of the DC pump.

dkeller22 · Jun 7, 2021

Since you have the opportunity you should consider two return pumps on two return lines. You can run smaller pumps and have redundancy if one fails. Half of the turnover is better than none and there will be less panic while you get things fixed.

Jivatma · Jun 8, 2021

DCR said:
You can install a check valve, but I would not depend on it to prevent an overflow. Your sump needs to hold the drain down volume. Keep in mind that unless you provide a siphon breaker hole near the surface, it will drain down to the exit depth of the Locline

I used a spa type return bulkhead back in the 80's for limited directional control. Now I prefer to just return through an open bulkhead and create the internal flow with powerheads. All you are doing with these exit nozzles is providing some directional flexibility and trading a reduced flow for an increased exit velocity. If I used a Locline I would not use the flared end pieces. The end pieces will reduce your flow rate considerably.

You are probably looking at 250-350 gph at 100% on that pump depending on the plumbing and if you put Loclines on it. Two 3/4" returns would be OK, but if you go with one return I would increase it to 1" to take advantage of the DC pump.

So, regardless of spa or locline, the returns need to be near the top of the tank, for pump failure reasons.

Would you still use spa-like returns or just use the tried&tested locline?

Lastly, how does staying with 1" returns take advantage of the DC pump if I'm already likely to be running at 100% anyways?

Jivatma · Jun 8, 2021

dkeller22 said:
Since you have the opportunity you should consider two return pumps on two return lines. You can run smaller pumps and have redundancy if one fails. Half of the turnover is better than none and there will be less panic while you get things fixed.

I have thought about running 2, but for the time being, I think I'm going to try and stay a bit more traditional and just run the one. I might change this at a later sate though if I need/want the extra flow.

DCR · Jun 8, 2021

Jivatma said:
So, regardless of spa or locline, the returns need to be near the top of the tank, for pump failure reasons.

Would you still use spa-like returns or just use the tried&tested locline?

Lastly, how does staying with 1" returns take advantage of the DC pump if I'm already likely to be running at 100% anyways?

I would recommend the returns be near the top. A 40 gal sump is fairly large for a 75 gal so you do not have to be right at the top, but I would not go much deeper than 3" bellow the water level for the center of the drilling. I would leave at least 2" of glass around the drilling for strength. If you use a locline you can direct the end of the locline deeper into the tank but you will need to drill a hole (maybe 1/8-1/4" diameter) near the top to act as a siphon breaker and prevent draining your tank down to the exit of the locline when the pump goes down

This is the type of fitting I used, but it fit into a 1" bulkhead instead of a 1-1/2". Mine were 1" black ABS and the jet inserted into the bulkhead and could be removed. I still have a few around in my parts bin if you really want to go this route and cannot find anything, but they are about 20 years old. PM me if interested

I think you could use something like that on a 75 gal, but I would look for a 1". Spa jets are generally designed for high pressure drop which will restrict your flow with low head aquarium pumps. You would not want the air injectors and many have metal parts that are likely not compatible with salt water. I don't really like locline either and prefer to just have an open bulkhead. Sometimes I will put a 45 degree PVC elbow on the end of the bulkhead to direct the flow towards the center of the tank.

The 1" piping is going to be less restrictive to flow. It will either give you more flow or allow you to run your pump at a lower speed to get the same flow. I generally say that 3/4" pipe is suitable for up to 300-400 gph which is on the edge of what you are doing. One inch pipe is not that much more difficult to install and would give you a lot more flexibility if you decide to increase your flow in the future with a larger pump. I think you may want to to with a Varios 4 anyway for a 75. I personally prefer AC pumps and would use an Eheim 1262 or Fluval SP2 for reliability on a 75 gal.

Barnabie Mejia · Jun 9, 2021

If I could do it all over again on my 75g, I would put 2 return lines and plumb it to give you the option to run 2 return pumps if you want to in the future.... I have one on my tank and I would really place it a little further out and add another if I could.... it makes a difference in the surface skimming in my particular situation.

my vote - 2 return lines.

I also went with a modular marine overflow because I liked the small internal weir that it has and how the inner and outer boxes are the same level and wont overflow. it is dead silent, and I also have a large weir like you...