My Journal to DIY PVC Overflow for non-drilled tank to sump filtration design

[Captured Moments]

This is my first journal and since I don't have a lot of free time, I will update and show steps every little bit at a time.

Topic covering:
Complete contruction build of a DIY PVC Overflow system including the drain side and the return from the sump to the main display tank
Building a DIY wet/dry filtration system in the sump using a "rubbermaid" 4 drawer cart storage unit
Safety system using a Pump Stopper Kit from Aquahub to prevent display tank overflow

Quick Specs:
Main Display Tank - 135 gallon (55 in. Length x 24 in. Width x 26 in. Height), not drilled
Sump - Standard 90 gal. tank (4 ft. x 1.5 ft. deep x 2 ft. high) with no baffles or partitions
Return Pump: Quiet One 4000 (effectively pumps 650 gal per hr at 5 feet of head pressure (distance from outlet of pump to top of return)
Filtration: Wet/Dry system in the sump using a storage cart with drawers
Livestock: 18 in. Pacu and one 12 in. Mono Peacock Bass

The display tank:
I bought the main display tank of some member on BCA quite a few months back and it needed some TLC. It was within my budget at $75 and it has thick glass and the glass is in good shape with no scratches. It had wood cedar trim throughout on all edges and the wood needed additional moisture protection. I bought a can of marine varnish (Epifanes), sanded the wood clean, stained to a teak colour and applied about 6 coats of varnish. A tank of that size is pretty heavy and awkward to move by oneself but somehow I managed to tip the tank to the sides and bottom up and back and so on to apply the varnish and let dry and turn again.. etc.. That took a while to do. It's not furniture quality and super smooth (that would have entailed sanding between each coat) but finally I am happy enough with the result and hopefully it will last many years. To a suggestion by Gordon (GKlaw), I also applied a bead of silicone to the underside of the wood trim along the edges on the inner side of the tank to prevent water from seeping in between the wood trim and the glass.

The Overflow:
A while back I started researching on sump designs for freshwater setups, wet/dry filter designs, overflow boxes commonly available or having the tank drilled. I wanted to move away from Aquaclear 110 and canister filters. I wasn't happy with the overflow boxes and I didn't want to have my tank drilled. While doing my research I stumbled across a sticky on the "Monsterfishkeepers" website and they have a design plus lengthy discussion on the DIY PVC overflow that one can build.
Here is the basic template of the design of the overflow courtesy of Monsterfishkeepers and the sticky thread by Chompers.



After I made the commitment to the design, I started sketching out the entire system on paper and figuring out every pieces of PVC I needed to buy. From a flow rate handling capability standpoint it was also necessary to decide on the size of the PVC given the flow rate of my return pump. I went with 1.25 in. size PVC rather than 1 in. to give me ample flow surplus handling capability in case I decide later to upgrade to a larger return pump. Besides I don't believe the 1" size would even be satisfactory according to the chart below and would not provide any safety margin.
Here's an excerpt copy and paste again courtesy of Chompers at Monsterfishkeepers to help size PVC pipes.

Cross Sectional Area (in square inches) - Pipe sizes vs. their cross sectional area. Useful for dividing flow between pipes.
size __area
1/2 = .1963
3/4 = .4418
1.0 = .7854
1.25= 1.227
1.5 = 1.767
2.0 = 3.142

Maximum Gravitational Vertical Flow - This is what we look for when sizing drains or DIY overflows. The flow under the power of gravity reaches a maximum in the same way an object reaches Terminal Velocity as it falls through the air. The gravitational force is countered by the waters viscosity (resistance to flow) and the frictional resistance of the pipe. The viscosity creates a minimum vertical length to acheive the maximum flow. If the vertical pipe length is less than the minimum, the flow rate will be somewhat less than the pipes maximum potential.
size _GPM __GPH
1/2 = 2.50 = 150
3/4 = 5.63 = 337.5
1.0 = 10.0 = 600
1.25=15.6 = 937.5
1.5 = 22.5 = 1350
2.0 = 40.0 = 2400

Min. Vertical Length
1/2 = 2"
3/4 = 5"
1.0 = 9"
1.25= 14"
1.5 = 20"
2.0 = 36"

So for example in my case, my return pump flows 650 gal./hr at 5 ft. of head. The total volume of water in the system is roughly 165 gallons (135 gal. from the main tank + 30 gal. in the sump). The turnover rate of the water being cycled in the entire system is thus 650/165 = 3.94 times every hour.
Using the reference above for gravitational vertical flow, using 1.25 PVC will handle a flow rate of 937 gph assuming you have a vertical down pipe of at least 14". That is enough safety margin for my pump effective output at 650 gph.

I ordered all the PVC parts from this website PVC Fittings Direct, PVC Fittings Schedule 40, Buy PVC Couplings, Adapters, Elbows, Tees, Caps & Plugs Online. Basically you would be needing Schedule 40 PVC fittings. The site is easy to navigate and figure out. Ordering was easy and the parts arrived about a week later.

- PVC Union Fitting, Fipt x Fipt (threaded on both ends).
- PVC Ball Valve, Fipt x Fipt (threaded on both ends)

While I won't be listing all the PVC parts that I ordered and needing for the build, I will describe some aspects of the build later on with pictures. One note worth mentioning at this point is that union fittings and PVC ball valves are the most expensive components compared to all the other PVC components such as 90 deg. elbows, cap, nipples, adapters, T-fittings. For the build I needed 2 unions. One 1 1/4 in. union for the drain side and another 1 in. union for the return side.
Price of the union fitting is: $10.10 for the 1 in. size and $15.38 for the 1 1/4 in. size
Price of the PVC ball valve is: $12.06 for 1 1/4 in. size and $14.87 for 1 1/2 in. size
You can get these in the "slip" type or the threaded type but because of the cost I decided to use the threaded (Fipt) type. Using the slip type would entail using glue and that is permanent. For reusability and upgrade later in future projects, you can dismantle a threaded type without wasting it.

Also high on the cost were the "Christy's Red Hot Blue Glue" PVC pipe cement 1/2 pint which was on sale for $14.95 and the "Christy's Ultra Seal Pipe Thread Sealant 1/2 pint which was $19.95 (not on sale).


There were a few extra PVC parts that I ordered to account for some slight build variations during construction.. sometimes things don't always go according to plan. Needless to say, the total cost of all the parts came to $155

[Fansons]

If I do it, my wife will kill me... Too many pipes, she doesn't like it.

But, looks cool!

[Captured Moments]

Here's my research sketch for the build. Sorry it's not to scale and I am not an artist but it helps to visualize.

[AWW]

Hey, Not sure how much you know about this, but i am gathering some information and was wondering if you could help.

I am trying to install a HOB overflow that can handle 3,000 gallons per hour. The largest one i have found for retail (I ordered it) Only handles 1,600 gallons per hour. Now, the simple solution would be to add two of these suckers and call it a day, But that really affects the bracing on my tank.

So, here is what i am wondering.

The bracing, as well as the width of the acrylic on my 450 gallon tank is 6". Can you make a PVC overflow that will go that far? I am trying to get away from removing any acrylic what so ever. Also, what do you figure the best width of PVC is? I know i am going to need to run more than one over flow.

Any help would be great,

Thanks,

Alex

[gklaw]

Hi Christian:

Very nice planning My brain is hurting trying to figure out how this thing would start siphoning and how it could restart after a power failure. Like to see that in action when I come over Monday

Like what I was taught in elementary long long time ago: never too late to learn something new.

[Captured Moments]

If I do it, my wife will kill me... Too many pipes, she doesn't like it.

But, looks cool!

Then I am lucky because my wife will let me do almost anything regarding my aquarium hobby. She likes looking at my planted tanks although they could look better if I spend more time on them.

[Captured Moments]

Hey, Not sure how much you know about this, but i am gathering some information and was wondering if you could help.

I am trying to install a HOB overflow that can handle 3,000 gallons per hour. The largest one i have found for retail (I ordered it) Only handles 1,600 gallons per hour. Now, the simple solution would be to add two of these suckers and call it a day, But that really affects the bracing on my tank.

So, here is what i am wondering.

The bracing, as well as the width of the acrylic on my 450 gallon tank is 6". Can you make a PVC overflow that will go that far? I am trying to get away from removing any acrylic what so ever. Also, what do you figure the best width of PVC is? I know i am going to need to run more than one over flow.

Any help would be great,

Thanks,

Alex

I am envious of your 450 gal. tank. Maybe I will get something that size in the future.
I am not experienced and an expert on this PVC overflow but I learned a lot during my research and observing my system running steady for at least a couple of weeks now with the livestock. Prior to that I run tests for a week.
For the U-bend going over the top of your tank (bracing and width of acrylic at 6"), I don't think there is any problem with that distance. On mine using 1.25 in. PVC, it is already 3 inches. In your case you will need to use larger size PVC to handle your much higher flow rate requirement. At 2 in. PVC., you will probably find that distance to be close to 5". How this PVC overflow system works is not dependent on this distance. You might observe slightly lower flow rate capability if this distance were upward of 1 ft. or something like that but I don't believe this distance is of concern.
Most likely you will need to run 2 overflows. I don't suggest you use PVC larger than 2 in. because the price difference is quite big after that.
Maybe you can build one overflow using 2" PVC and the second overflow using 1.5" PVC. The 2" overflow will be your main overflow and the water intake level will be placed about 1/2 inch lower than the second smaller overflow. Why lower? because your primary overflow will take in most of the water and will be full and be mostly silent. The secondary smaller overflow will take the rest of the flow but will not have to work so hard and stay quieter without having to result to being full.
Hope this makes sense.

[Captured Moments]

Hi Christian:

Very nice planning My brain is hurting trying to figure out how this thing would start siphoning and how it could restart after a power failure. Like to see that in action when I come over Monday

Like what I was taught in elementary long long time ago: never too late to learn something new.

Hey Gordon,
For sure I will show you when you come over. I'll show you my marijuana grow-op as well... jk.
During the testing phase I simulated many power outages by stopping the pump. Since my return extends quite far down the water level in the main tank, I drilled a couple of "siphon break" holes about 1 in. below the water level, so in the vent of a power outage the siphon effect of the water from the display tank flowing back into the sump via the return line will be broken.
The PVC overflow system retains the prime even during a power outage. I already went through a real power outage for a few hours last week while I was at work. The entire system resumes itself once power comes back on.
At the top of the bend going over the tank, there is a Hagen Elite check valve. The check valve is used to prime the system and purge all the air off. The bottom 2 "u-bends" and the top bend is always full of water even when it is not running. The water level inside the bottom 2 "u-bends" is dictated by the height of the "T-Fitting" (F on the first diagram) because that is when the water will start actually overflowing into the sump.

[Captured Moments]

I regret not having taken some pictures during the actual build of the overflow system but I will try to cover every aspects with pictures. Here's a representation schematics of my overflow. The black outline is the complete overflow and I have placed some pictures in the areas to show the actual parts.

[gklaw]

I think I got it now - ingenious