I have had my Fluval Flex 32.5g tank set up for about 7 months now and always battled heat. My tank ran in the 81-82 degree range and actually did fine, but I finally decided to get the heat under control so I can start trying some more finnicky corals. I got the idea to add PC fans to my rear lid compartment from people on here and wanted to document what I did for others with this tank.
I first ordered an inkbird temperature controller and 2 pc fans found on amazon.
Amazon product
Amazon product
The PC fans come wired together and if I were to do it all again, I would consider buying 2 single fans that can connect together so I could test using just one or different speeds. One fan over the middle chamber may end up being enough but I will never know now. But they work fine as expected and were cheaper than buying 2 individually.
To start, I took the back chamber cover off and marked exactly where I wanted the fans to sit. I tried to pick the flattest spot so the fans would sit flush, I then drilled a pilot hole to mark the center. After that, I used a 3 inch hole saw drill bit and cut out the 2 circles using the pilot hole.
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Next, I took the screws and cage off the bottom side of each fan. I tossed the cages to get the fans to lay flat and marked the screw holes with the fans centered above each circle. I drilled out those 4 holes on each to make attaching the fans to the top easier.
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Finally, I inserted the screws from the bottom of the lid holes and attached back to the fans to hold them in place.
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One of the major positives about this tank and the tight fitting hood is the basically zero evaporation. I wanted to try and keep this evaporation minimal so I do not have to buy an auto top off. So I set my inkbird to 78 degrees with a 1 degree cooling differential. The way the inkbird works is that it does not start cooling until this 1 degree difference is met. So when the temp hits 79, the fans kick on and cool the tank all the way back to 78 before they turn off. I tried it with 77 and also a 2 degree differential but the fans were running more than I liked and causing more evaporation. I am getting slightly more evaporation now but nothing that water changes or adding a small bit of rodi water once a week doesn't take care of(less than 1/2 gallon a week).
I have been very fortunate to have a healthy tank since the start that even went through a 3 day power loss during a winter storm in February. Even though I lost a lot of coral during that, my tank immediately bounced right back which was a nice surprise. Here are a few shots under mostly blues that I run and a few with whites turned up.
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This is genius. I’ve been looking for something for my Flex 32.5 because of temperature issues and this is it. Thanks!!