Liquid Level Controller Survey (ATO's) - Part 1

[rroselavy]

Level Controller Survey - Part I

Hey all,

I recently discovered that my Elos Osmocontroller was not shutting off, so I tried in vain to clean the float switch, thinking that a vinegar/water bath and some careful toothbrushing was going to fix things. After setting the switch back up, I quickly discovered that it was still not behaving properly.

I began to think about the potential hazards of a single switch level controller, and decided it was important to have some redundancy in order to help prevent failures in the future. I therefore did some research of current offerings in Level Controllers/Auto Top Off systems, and this three part post will serve as a mini-survey of sorts. Regardless of whether my notes here are helpful, please do not consider me an expert on these matters. I am not an electrician, and will not take any responsibility for the Level Controller you choose to build, purchase and operate. If anyone has any suggestions on how to improve this article, or see's their favorite Level Controller omitted, please let me know and I will revise the text where appropriate.

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First, let me direct you to Rob's fine intro to his ATO system:

top-offs-overflows-podcast-episode-63

Background Info

A Level Controller (also called an Auto-Topoff Controller or Osmollator/Osmo-Controller in Europe) is a electric and/or electronic device that maintains the height of the water in your aquarium display or sump by activating a water pump to replenish water lost due to evaporation. They all operate very similarly, and offer the following basic benefits:

• Water is automatically replenished, relieving the aquarist form having to perform the task.

• Water level in the sump remains more consistent, which improves water parameter stability and is optimal for protein skimmer performance.

• Can be used as feed water for a Kalkwasser reactor or draw from a Kalk reservoir to help maintain calcium and alkalinity levels.

The biggest differences in the current Level Controller offerings is a matter of precision and safety.

A Float Switch or Level Sensor is the mechanism that actuates an electric relay when the water level is high, causing electric current to flow to a pump. There are several such switches/sensors that work a bit differently.

The most common is the Float Switch, which uses a magnet encased insider a donut-shaped plastic ring to magnetically activate a switch encased in plastic. They are fairly reliable, but can fail if calcium buildup (or snails) are allowed to hamper their operation. The wires at the top of the float switch need to be properly sealed so the switch can be submerged when the Aquarium's return pump is not operating. Float Switches are also sensitive to waves in the sump or aquarium unless a splash guard is employed to help minimize the effect of any temporary waves.


magnet actuated float switches

A horizontal version of the float switch (like model M8700-C in the above pic) solves mounting and sealing issues by being installed bulkhead-style in a hole in the side of the tank or sump.

A Level Sensor does the same thing, but may operate optically or with an air pressure activated switch in order to complete the circuit. Optical level sensors are as accurate and reliable as they are expensive, but they need to be cleaned semi-regularly to insure that calcium buildup does not obscure the sensor. Air-actuated switches use a tube that has one end attached to a switch and the other end submerged into the water. When the water level goes down, the air pressure in the tube decreases and the switch is released, activating the fill pump. When the water level raises, the air pressure builds until it "presses" the switch, thus turning off the pump. Only one manufacture that I have encountered uses this kind of switch, and I have not seen much feedback on the switch type.


optical sensors (sensors on left have polycarbonate casings)


Spectrapure's Air Pressure activated "Power Liquid Level Controller".


Features

Safety

While it is possible to have a float switch directly actuate a full 120 volt electric circuit, it is neither necessary nor safe to have all that voltage so close to the water. DIY solutions, such as this one at Melev's Reef are simple and affordable, but not very safe if the float switch contacts become exposed to water, or if a power surge fuses the float switch contacts together. For this reason, the float switches/sensors of better level controllers work on far lower and thus safer voltage by using low voltage relays. A Reefkeeping article entitled "Aquarium Electrical Systems" has a far safer DIY diagram with a low voltage loop. Some LLC's have pumps that are integrated with the level controller that also operate at a lower voltage.

Please note: It is important to note that float switches need to be properly sealed before they can be fully submerged. Any DIY approaches to level controllers should make sure that the float switches used can be submerged since that is what usually happens when our sump's return pump is shut off.

Ask a manufacturer to make sure that the switches are sealed and operate on low voltage.

Redundancy

Single switch Level Controllers can operate reliably for a while, but the switch will eventually fail due to calcium build up, adventurous snails, or an electrical short. It is safer to assume that all float switches exposed to salt water will eventually fail. For this reason, it is recommended that aquarists have a level controller with a second switch that acts as a safety-shut off for when the primary switch fails. The second switch should be positioned higher than the first and should not normally be submerged so it remains reliable.

Another option for redundancy is to have two Level Controllers act in succession, where one will shut the other off if it should fail. This would help safeguard for both switch failure and electronic failure. Similarly, a hobbyist could use a reef Multi-Controller (with float switch capabilities, such as a Neptune Systems Aquacontroller or Digital Aquatics RKE) to act as a shut-off for a standalone single or double level controller.

Secondary Features

Some Level Controllers have extra features that enhance usability or redundancy:

• Fill Duration Timers that will limit the time the pumps will operate.
• LED Indicators of pump/sensor activity and/or Audible Alarms if backup switch is triggered.
• Multiple modes of operation so second switch either acts as a safety backup or keeps the pump from running dry.
• Easy to replace plug-in float switches, or hardwired switches for increased reliability.
• Offers a Controlled Outlet (for 3rd party pumps), or integrated low voltage/low throughput pumps (usually hardwired into the controller box) that may or may not be more difficult/expensive to replace.
• Overfill feature in order to reduce the frequency by which the pump is in operation.
• Some Level Controllers come in DIY kit form that can save the hobbyist money if they feel comfortable with a solder gun.

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Next we will look at some current offerings...

[rroselavy]

Level Controller Survey, Part II

My own search for a level controller tried to balance safety, reliability, and affordability. I had the following requirements:

1) Dual Float Switch (or Optical Sensor and backup Float Switch)
2) Level Switch operates on a low voltage circuit.
3) Switches need to be sealed (submergible).
4) Needs to run a low flow pump to maintain a more consistent water level, reduce splashing, and is more suitable for Kalk drip rates.
5) Needs to have a stable mount that does not use suction cups.

The following are the products I considered:


Tunze Osmolator Universal 3155 - US $195



This Level Controller includes a very accurate optical sensor for primary level control, a float switch for redundancy, modular mounting brackets and visual and audible alerts and other electronic features. It is as well regarded as it is expensive. The integrated ~12 gpm pumps can be replaced for around $20, which makes the overall package attractive. The Tunze directions indicate that the optical sensor needs to be kept clean and should not be operated in the path of Kalk drip concentrate.


Autotopoff.com's Optical Sensor w/ Float Switch Backup - US $144 (pump not included)



Although lacking alerts and overfilling of the Tunze 3155, this Level Controller also includes a very accurate optical sensor for primary level control, and a float switch for redundancy for about $50 less. The mounting bracket can be custom configured, as well as several other options from this manufacturer. Sensor/Switches are hardwired into the controller box. Outlet for 3rd party pumps. They also make $50 dual float switch models in either tank or sump mount configurations, complete with splash/snail guards. I have had the Dual Tank Mount operating on my 20g QT very reliably for the past eight months. "Made in USA".


Reef Fanatic Level Controller - US $80 (pump not included)




Dual float switch controller that can operate in two modes: Redundancy or Run Dry protection. Visual indicators of pump and switch activity. 10 second Relay Overfill feature. Suction cup used on mounts brackets that are otherwise sturdy. Plugin switches for easy replacement. Outlet for 3rd party pumps.


Spectrapure Ultra-Precise Liquid Level Controller II - $240 (integrated peristaltic pump)



Truly the Cadillac of Level Controllers. The last version of this expensive product used dual float switches (albeit with suction cup mounts) that plug into a peristaltic pump. It is unclear what type of sensor(s) the new version has, but the pump has been improved and has some interesting features. The pump itself is advertised as virtually maintenance free, can pump liquids up to 50 feet in height, is Kalkwasser and Chemical safe, and has an adjustable "ON TIME" (Overfill) AND flow rate. The unit is fairly compact since the controller and the pump are integrated, and comes with an outstanding 5 year warranty. Plugin Switches for easy replacement.

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Other Options

There are a few others I did not consider even though they are worth mentioning. JBJ makes an affordable $85 Level Controller that is very similar to the Reef Fanatic offering, but comes with modular mounting straps instead of suction cup mounts. Aquahub.com offers several DIY models for those who wish to build one for even less money. Spectrapure's far less expensive Power Liquid Level Controller uses a single air pressure activated switch, and the GAP Level Loc is a switch/float/solenoid solution for those brave enough to connect a RODI system directly to the sump.

Interesting to note that Aquahub warns that the top of their float switches should not be submerged, and they sell a separate $2 tube and adapter product to protect the switch from moisture. Other manufacturers appear to inject sealing material (Silicone?) into the top opening of the float switches to seal the wires.

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Next we will look at my choice and see how it stacks up.

[rroselavy]

Liquid Level Controller Survey, Part III

Conclusion

Before I explain the thinking behind my purchase, let's look at my priorities again:

1) Dual Float Switch (or Optical Sensor and backup Float Switch)
2) Level Switch operates on a low voltage circuit.
3) Switches need to be sealed (submergible).
4) Needs to run a low flow pump to maintain a more consistent water level, reduce splashing, and is more suitable for Kalk drip rates.
5) Needs to have a stable mount that does not use suction cups.


All of the level controllers I considered from Part II of this survey satisfied most if not all the criteria with the following exceptions:

• The Tunze 3155 Osmo-Controller is very expensive, and has a 12gpm pump that would need to be significantly bypassed to obtain a slow kalk drip rate.

• The AutoTopOff.com Optical LLC is also expensive even though it can use a more appropriate (an less expensive) 3+gm Aqualifter pump that needs to be bypassed much less. Both their Optical LLC and the Dual-Float LLC have hardwired floats that may (?) be difficult to replace when one fails. The leads for the float switches are also very short (20") unless you purchase the optional extensions.

• The Reef Fanatic LLC has plug-in switches with very long leads, and RF sells replacement switches complete with mounting brackets. With that said, the mini-jacks used to plug in the switches may represent another point of failure, and the suction cups they offer with their otherwise sturdy mount assembly should be avoided at all cost.

• The Spectrapure "Ultra-Precise" LLC most likely is perfect for ultra- flow control and for pumping ultra-distances, but is otherwise ultra-expensive. Also, the mounts included (with the previous model at least) were uninspiring for a premium product.

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Each of the models are excellent choices and offer safety and redundancy, but some ultimately lacked affordability. I finally decided that $100 or less should get me as much product I needed, so the $80 Reef Fanatic and the $57 (with 12v option) Autotopoff.com Dual Float Switch models then became the contenders. Both can operate a Aqualifter pump. The Autotopoff.com model comes with a splash/snail guard, and is "Made in USA". The Reef Fanatic unit comes with longer leads, easy to replace switches, and has LED indicators for switch and pump activation, so you can see what the controller is sensing and doing.

Drum Roll Please...


The Reef Fanatic Controller Box


The Reef Fanatic Controlled Outlet

I ended up purchasing the Reef Fanatic controller at a reduced price during a recent Group Buy, and so far have been pleased with the product. I did not realize how useful the LED indicators would be until I started using the controller. The Aqualifter pump is nearly silent, so it is nice to have a visual indicator for when the pump turns on or when the switches are active while I am messing around in the sump. I tossed the suction cups and used zip ties to mount the mount brackets to a piece of egg crate. This is how my previous LLC switch was mounted and it works well in my sump. The float switches appear to be well sealed, but I will be careful to inspct the seals as the float wires get tugged in the future. The $13 Aqualifter is easy to replace, and requires minimal bleeding to provide my kalk reactor with the right drip rate.

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Anyhow, I hope this "survey" has been helpful to anyone looking into liquid level controllers for aquariums. Please feel free to ask questions, or offer improvements on the text to make it more complete, correct and informative.

[Phurst]

Wow, lots of great info here!