Aquarium Bulk Heads

This confusing looking jumble of tubing and equipment is a graphical representation of the plumbing in my stand. Clicking the picture should bring up a much more legible, larger diagram.

I have to begin with a disclaimer. This is not your typical planted aquarium plumbing layout. It’s extreme. IMO one of the highest expressions of the hobby is a “low tech” tank with little-to-no plumbing at all. This is at the opposite end of the spectrum. Even “high tech” tanks are almost always less technical than this. I went to extremes deliberately because I had a number of goals that I wanted to accomplish, and I wanted to do everything reasonably possible to accomplish them all:

Remove as much equipment out of the tank as was reasonably possible
I’ve removed heaters, pH probes, temp probes, and even eliminated outflows from the tank by having water leave the tank through bulkheads in the bottom.
Automate water changes
There is a simple system to let water drain from the tank automatically, and a separate fill system that fills and tops off the tank again every night. This is done without having a sump.
Heat a lot of water fast
I live in the Northeast, and filling the tank with tapwater in the winter will give discus a nasty chill without being able to throw a lot of heating watts at the tank quickly.
Accommodate changes easily
The excessive use of PVC unions allows me to remove most any piece fairly easily… just unscrew the union at either end and pull it out. It’s also worth noting that I always put the small half of every union 2-piece pair on the downstream end of each piece of equipment. That way when I create any replacement piece it only takes 1 union (2 halves) and I know which end goes where - every time.
Provide some redundancy
If you look you will see that there are two filtration loops. The tank can run for a limited time on either one of the two. While a lot of things are only on one loop (UV, heat, and CO2 injection), temporarily dropping a heater in the tank, delaying, water changes, and adding CO2 though Seachem Excel will allow running without that loop for enough days to repair any problem without any real issue. Or, worst case in a pump problem, I can swap out the two pumps since they are virtually identical.
Make it bullet proof
There are almost no slip fitted flexible tubes for the filtration loops. It’s all threaded PVC. And it’s all firmly attached to the stand. No floppy wires or tubes in the main plumbing. There are some slip fitted flexible tubing for things like the fill and drain systems. But that tubing is such a small diameter that if any mishap did ever occur, any leak would be slow. And BTW, as of this writing this plumbing has been in place for a year and never leaked a drop… even though the cat and the ferret both think of this jumble as their personal playground.
Dose liquid ferts automatically
This diagram does not show the electronic controller that turns the fert pumps on and off each day. But at least it shows how the liquid fertilizer is plumbed.
Be flexible
The many ball valves allow me to re-route water flows when things are being worked on.
Keep everything in the stand
There are a few obvious exceptions, like lights and the hidden tubes that take waste water to the drain and bring freshwater to the tank. Those can’t be in the stand. But pretty much everything else is.

This diagram does not detail the electrical system, which drives everything. You can find that tank electrical diagram here. Obviously I’ve got a lot of solenoids (CO2, drain, fill, ferts) that have to be controlled by some electrical controller. Same goes for heat. So making complete sense of this requires a review of that diagram too. This is just plumbing.

It may look confusing, but it’s really just a few simple systems.

Diagram Explanation

I’m going to try to explain this in the order that the water flows through the system. It’s not going to make much sense though without a good diagram, so if you haven’t done so already, please click on the diagram above and walk through this explanation as you refer back to the diagram. It all begins with water in the tank. But the tank is not shown. Instead…

Outflow Manifold

Water flows out of the tank through three bulkhead holes in the bottom of the tank. This is technically 50% more capacity for water flowing out than needed, but it makes sure the pumps are not restricted by too little water. All three of these outflows come into a single manifold constructed out of four and five way PVC pipes. The water leaves this DIY manifold in two ways. One flows to the primary pump loop which has most of the filtration, and the other to the secondary loop which only has redundant bio-mechanical filtration. By pulling water into this manifold a modicum of water mixing occurs, which is good for CO2, fert, warm water distribution, and in-line sensing.

In-line Sensing

While the water is in the manifold it runs past an in-line mounted pH sensor. This sensor is plugged into a controller that turns the CO2 on and off depending on the pH. Likewise it runs by a temp controller, which in turn is connected to a controller that turns the various heaters on and off depending on the water temp. And finally there is a ground probe, plugged into the home A/C ground to help control any stray electrical current - should such exist within the tank.

Tank Fill

It seems odd to discuss tank filling before talking about draining first, but the fill water comes into the manifold, so I’ll cover it here. The household water is connected to the inflow manifold, but not before it runs through two carbon filters and a solenoid. The solenoid is normally closed, so water cannot flow in if power is lost. But a controller turns the solenoid on periodically and lets fresh water flow in. Before it flows in though, the water first flows through a 10 micron carbon filter, which strips out chlorine from the water along with large particulates. Then it flows though a 2 micron carbon filter that strips out any last remnants of chlorine. These two filters help ensure that no particles clog the solenoid and keep it from closing.

Pumps

As mentioned before, once water exits the manifold it goes to one of two directions. Each goes to a pump. I think these are identical. They have the same specs and look identical. They are wicked quiet, but they vibrate a lot and require serious vibration damping in their mounting. And they also contribute heat to the water. But for discus that’s not too much of a problem.

Bio/Mechanical Filtration

The Ocean Clear filters that come after the pumps are great. They filter so well that changing/cleaning media only has do be done every 4-6 months. And their 50 micro filters keep the water crystal clear. I love that. Plus they provide additional biological filtration. One of these filters goes nearly straight back to the tank. So I’ll ignore that path, but will talk about the primary filtration loop (on the bottom of the diagram) that runs the water through all the other equipment.

Tank Drain

Like the fill system, this is also controlled by a solenoid. That normally closed solenoid will not let any water drain out unless it is powered on. So, again, no water is lost in a power failure. The same controller that turns the fill solenoid on and off controls this too. It’s placed immediately after the filter so that any particulates that could clog the solenoid have been stripped out of the water.

Heating

Three separate 300 watt heaters allows the water to be heated up quickly. They are in-line mounted Pentair modules, horizontally mounted to fit in the stand. Water flows sequentially through them. It’s worth noting that they are turned on and off by the controller that senses temperature as detected by the temp probe in the manifold - before it gets to the heaters. If I tried use the thermostats on each heater, being in-line means the I would to set the 2nd and 3rd thermostats to not turn on until the water was really hot, because the water is being preheated by the heaters in front of it. By controlling them by a temp sensor in the “cool” side of the loop, I’m always detecting tank temps, allowing me to set the thermostats on the heaters at a reasonable temperature… one that will not fry the fish if one ever gets stuck in the on position.

Ultraviolet Filtration

After the heaters is a 25 watt UV. The flow rate on this filtration loop is slow enough to allow a UV of this wattage to toast pretty much anything unfortunate enough to flow through it.

CO2 Injection

Rather than normal CO2 injections, I’ve used Tom Barr’s suggestion of a Mazzei venturi to dissolve CO2 in the water flowing by. This requires having water flowing by at the correct speed, so the ball valve (#19) is used to control how much goes through the venturi vs. going around it. CO2 is regulated by the solenoid on the CO2 regulator. As I mentioned before, this turns on and off - allowing CO2 to be injected or not - depending on the pH level measured coming out of the tank by the pH probe in the outflow manifold.

Fertilizer Injection

Fert injection is controlled by two peristaltic pumps which are turned on for a few minutes a day by an electronic controller. Peristaltic pumps allow injection of very precise liquid fert quantities. And it being automatic makes daily maintenance a lot easier too - no dosing!

Inflow Manifold

This just consolidates the flow from both filtration paths, does a bit of water mixing and returns the water to the tank. The important thing is that depending on the needs of the aquascape, water can be directed to either side of the tank, or flowing more to one particular side if slow flow is needed on the other. Also, the ball valves allow either of the two flows to be excluded if one is having maintenance performed. And needless to say, the large check valves on the end of the stand plumbing - last thing before water goes back to the tank - prevents a backflow siphon of water from happening should I be performing maintenance. The inflows themselves do go into the tank, and that violates my first goal of removing as much equipment as possible. I made that compromise because having water come in the top of the tank, and exit the bottom creates great circulation. But I did have extra, unused, bulkhead holes drilled in the bottom of the tank, should I ever decide to remove that last bit of visible hardware and plumb my inflows through the bottom.

Tank Aeration

Over on the upper right side of the diagram is a bulkhead attached to an air pump. Though it does not show in the diagram, the upper side of the bulkhead in the tank has a slip nozzle with an air stone on it. Planted tank filtration typically don’t do much aeration, depending instead on the plants to provide oxygen to the water. But a tank full of discus is quite a bit different then your typical planted tank with a small school of tetras. I’m personally convinced that my discus seem so little stressed, in part, because I aerate my water day and night. Not enough to out-gas a lot of CO2. Just a little air. And the great thing about bringing the air though the bottom of the tank is that I don’t have air hoses coming into the tank. It’s all hidden.

Water Level Sensing

Just to the side of the aeration bulkhead hole in the diagram is the bulkhead for the water level sensor. This is simply a hole in the bottom of the tank with a tube under the bulkhead, which is connected to a water pressure sensor. In the process of doing the automatic fills of the tank, when the water reaches the proper height (depth and pressure), the sensor switches on and electrically signals the fill controller that the tank is full, and the controller shuts off the solenoid to stop filling the tank. This enables me to have automatic drain/fill cycles every night, knowing the tank will be filled to the correct height and I don’t have to have any unsightly things in the tank like float switches. But that fill process is on a timer just in case this puppy ever fails, it won’t keep filling for too long.

Closing

I know that some of these systems require a bit more information. This certainly does not explain how it all fits in the stand. I just finished an electrical diagram that helps fill in some of the gaps. And over time I’ll work up some individual - more detailed - explanations of the CO2 venturi, fert injection, and the drain/fill systems.

In closing, if this is interest of to you, then by all means swing by my Son of Kahuna thread over at Plantedtank.net, where I discuss this setup ad nauseam with other posters. Also a large number of people there have set up some wonderful alternative ways to accomplish many of the same things.

And a lot of what I have here - like the auto water change and massive heating - are primarily because I am keeping discus in this planted tank. So if you want to see wonderful discussions of how to keep discus in planted tanks, the best site I know is Simplydiscus.com. I’ve got a Son of Kahuna thread there to.

Finally it’s worth mentioning that I know of no better English speaking site for hard-core plumbing than Reefcentral.com. I don’t post there much since I’m not a reef-keeper. But they can answer tough aquarium plumbing questions like nobody’s business.

So pick a forum, and come say “hi”!