Tunze 3155.000 Osmolator Auto Top Off System

I purposely waited to leave a review for this product. I have had it for over three months and it does exactly what it is supposed to do. Extremely accurate and makes for effortless top off solutions on your tank to ensure your salinity doesn't change due to forgetting to top off you system. For people that don't know, when the water in a salt water tank evaporates, the salt is left behind which raises the salinity of the salt water in the tank. Using fresh, salt free RODI water to replace the evaporating water is a must for a reef tank to keep the salinity stable. This devise will not disappoint!

Originally, I used a 3152 for my ATO in a 34g Mixed Reef. That version relies solely on a float switch which caused me numerous failures allowing the unit to run up to its backup time limit then cut off.. I thought that was OK until one day the backup failed and I came home to a flood. After that, I switched to the 3155 and it was a great investment. The sensor works flawlessly and the double backup gives peace of mind (and an audible alarm if something goes wrong).Set up was not difficult -- took about 15 minutes to make sure I had everything positioned and connected. The toughest part was pushing the tubing into the pump.. I think I got it about halfway in and gave up, but it seems secure.The only issue I had after set up was that I had dialed down to the slowest pump setting since I have a smaller tank. This resulted in water not coming up high enough so I had to open it up a couple times to turn up the pump speed in order to move the water up about 5' to the tank.Overall, this greatly minimizes the daily needs for the tank and gives peace of mind. It has become an essential piece of my tank now and in the future

Nothing beats just DUMPING a 5 gallon bucket of water into my reservoir rather than stacking some crap up and lifting a bucket and siphoning and having to monitor levels. Also I never have temp swings associated with topping up my tank. Its also great for water changes, I just make sure that I have enough in my secondary tank, siphon out whatever I want to change, and BAM, auto fill. Best fish tank investment I have ever made

Unit arrived on time and looked good at first sight. I installed the the unit and ran all the wires (tucked, Hidden, and zip tied) with proper cable management techniques, only to find out the unit does work properly. When the water level is low it does not turn on the pump, And the main power connection does not make a good connection and shut off with the slightest touch. When I started looking for the cause I opened the back panel of the unit to check connection and I found salt creep in the circuit board and then noticed algae on the float white float switch. This was a used unit. I want to send back but now have to cut all the cable ties and undo all my hard work for a proper install. They should send me a new control box first so I don't have to take it all apart to send back. Very disappointed!

After about 5-6 years of trusty service my controller finally pooped out. Having used this product for many years I can honestly say it is a very percise product and works great. The set up is not diffucult but does require a bit of thought. In the years that I ve used the Tunze there are a couple things I would recommend people watch out for.1) the sensor can get a bit crusty over time and when this happens the top off will not work as it should. If you notice some crud on the sensor, take it out and submerge it in white vinegar for a couple hours and then whipe it clean. it should be good to go after that.2) the pump will not last as long as the controller. If you keep you controller for many years you can expect to replace the pupm a couple times. Good news is that they sell the pump seperatly so you dont have to buy a whole new set up3) finally the pump is a bit sensitive. If it gets an air bubble in it it will not work. This can happen when the container you are pumping from runs dry. If your container runs dry, refill it and then while submerged tilt the pump upside down (the intake will be facing up). you should see an air bubble pop out and when that happens you are good to go.

I gave this 4 out of 5 when in reality it should be 4.5 stars. I'll explain that in a bit.There is a lot to like about his ATO. The redundancy fail safes is a huge one for me. This is used on my 55 Gallon Mixed Reef. Since I am gone at work for 12 hours of the day plus sleep at night I wanted something I could feel secure with. So far this does. This offers more than what you can see on the surface. There are actual adjustments inside the display module. BRS has a good video on this and how to set up. I haven't messed with it however. Everything seems to be solid and it works perfect. I really like the water tube holder as opposed to the one my Micro ATO by SmartATO. It's quiet, only time i hear it is when I hear water trickling in and only for a few seconds. I use a 5 gallon reservoir bucket, no kalk with RO/DI water. I like the over all functionality of this.The issue I had/have and why I give it 4 (4.5) stars is dialing it in. my tank has a rim on it like most traditional ones do however even getting the water level right at the sensor (not sure where that trigger is on it still) has been difficult. I've already done a water change and even getting the water level right for the sensor, it still wants to spit fresh water in. Not a super big deal but if the water level is set right it shouldn't be doing this. But once it is "set" it does its job flawless. I didn't have this issue with the micro ATO that I am running on a smaller tank.Over worth the price tag.