Deluxe Madison Float Switch - Vertical Mount - Without Nut

Deluxe Madison Float Switch
Click on image to zoom
View full size image

More Views

  • Deluxe Madison Float Switch
  • Float Switches for Auto Top Off & other Projects
  • Deluxe Madison Float Switch Diagram

Deluxe Madison Float Switch - Vertical Mount - Without Nut

63% Recommend this to a friend (5 of 8)

SKU: 300101

reg. $14.49

Special Price: $12.32

In Stock: 80
Please wait...
Ships Monday

365 Day Returns

What's This?

Preferred Reefers
Earn Up To 5% Back

Quick Overview

Recommended for water applications like level controllers, auto top systems or other aquarium uses.

  • Normally closed or normally open (see more)

  • Float magnet is encased inside the float

  • 24" leads (22 gauge wire) offer project flexibility

  • 1/8" NPT tapered fitting - does not come with a nut

Certifications: UL, CSA, NSF


Full Details

Deluxe Madison Float Switch is great for:


  • General water level control application
  • Aquarium top-off applications
  • Humidification/de-humidification applications
  • Hydroponics projects
  • Water features
  • Air conditioning drain pan applications


Don’t use in heavy duty applications like sewage pumps.


Great for water. Check your fluid's specific gravity.


The wires complete a circuit when the float is down. You can reverse the operation by removing the clip, turning the float upside down and replacing the clip.


A pump rated at just 5 watts can destroy a float switch rated for 50 watts, locking it in the “on” position and pumping a lot of water where you do not want it.


The magnetic reeds enclosed in liquid level sensors are extremely reliable and long-lasting when utilized properly. Failures are nearly always a result of current overloading. Pumps, solenoids and many other devices that require control by a liquid level sensor carry "steady state" current ratings. These devices can draw ten times (or more) their steady state power ratings on start-up or shut-down. When the reeds inside our switches are exposed to this kind of "spiking voltage" they can overheat and become deformed. In some cases they may even weld together or break off, causing the switch circuit to remain closed (or open) regardless of the level of the float. Deformed reeds can also function intermittently, causing problems with troubleshooting. A 50 watt float switch can be destroyed by a pump rated at 6 watts and, unfortunately, it may take many cycles before the failure occurs.


Because they can destroy an otherwise very reliable float switch, care must be taken to completely isolate the switch from the current drawn by pumps, solenoids or other devices subject to spiking voltage. Resistors or diodes may be used, but the most common solution is to utilize a circuit board or a relay.


In the illustration, a relay acts as a switch for a pump, thereby isolating the float switch from any spikes that the pump may draw. The float switch turns the relay coil on and off. In this way, the only current handled by the float switch is that small amount required by the relay coil. Please consult with your relay supplier to assure that the relay current requirements are well within the specs of the float switch.


8 Items

  • No nut, no sale By Doug on 2/29/2016

    This does not include the nut. Some have stated that we need to go buy a PVC coupler of the correct size to fit this. That's great. Do you know what would be better? INCLUDE ONE WITH THE SWITCH! BRS is not the place to buy your switches.
  • Float Switch By Utah Reefer on 2/18/2015

    Very nice switch, float is heavy and works very smoothly. I would agree that they need to include the nut. Hard to find the 1/8" NPT tap as it would be easier to drill a hole and secure with nut
  • Proper mounting By wirewiggler on 1/25/2015

    Most of the people using this completly missed the proper way you mount this. What you want to do is use a pvc pipe coupler and nipple on the thread. What this does is to seal the wire so over time water does not leak into the reed switch.
  • Do NOT get this if you don't have a nut!!!!!!!! By P in Mpls on 3/12/2014

    As I and others have mentioned, these do not come with a nut. I have looked at 4 hardware stores, Lowes, Home Depot, Menards and a plumbing supply outlet, and NOBODY carries a nylon ⅛" female NPT fitting!

    The switch may work fine but is basically unusable because I can't attach it to anything.
  • Where's the nut? By P in Mpls on 2/12/2014

    This switch works well, exactly as advertised. Like others, I wish it would come with a nut. The only FPT fitting I can find is brass, which is unacceptable for a reef tank. Even a link on where to find one would be helpful.
  • extremely reliable By Mike on 6/27/2013

    I have used several to measure water levels for a Neptune ACIII for a few years without issue. Other reviewers have noted that these do not come with a nut. This is because they do not understand NPT (national pipe thread) vs. straight thread standards (such as machine screw or bolt threads).
    NPT threads are used with pipe fittings; they are tapered, and are designed to seal when screwed into a mating fitting without requiring a nut. As such, these switches attach to a 1/8" NPT female connection.
  • Make sure you can find the nut first By Mrk on 5/5/2013

    This seems like a nice switch. It's bigger than most but the deal breaker is the not included mounting nut. Since BRS and even the manufacturer don't sell the nuts it should have made me suspicious. Home Depot, Lowes, Ace, Amazon and even Fastenal don't have the nuts either. So I'm forced to return mine.
  • Nice switch, does the job. Easy to install. By Kevin on 2/7/2012

    The switch is great. I put my ATO together in a couple of hours and it works well. The switch is smooth and doesn't stick. I just wish it had a nut at the top to help mounting it to the rack.


Ask a question

Product Questions

Do you sell a relay or circuit board for this float or have a recommended supplier?

Question by: M on Feb 12, 2014 4:13:00 PM
There are a lot of options out there, most folks interface them with either the Neptune Apex systems or the Digital Aquatics systems. If you want something entirely DIY then you would want to look at the aquahub DIY top off kit which includes a simple relay and parts.
Answer by: Bulk Reef Supply on Feb 12, 2014 4:13:00 PM