I have been using the Fluval FX5 on my 75g for a little over a year now. I think that is long enough to give a fair and accurate review of the filter.
The FX5 is great for turtle use on smaller tanks (75g up to about 150g. Filter rated for up to 400g). I discarded the hose that came with it and used 1" PVC up until I reached the connector and used 1"ID vinyl tubing on it. I then ran vinyl back to a PVC line for the return. The 1" tubing fits perfectly over the valves supplied with the filter. I used hose clamps from the local auto parts store to secure all hose connections. I obtained this filter from craigslist for $50 and it was missing 2 of the screws to hold the lid in place. I still have not replaced these as they are expensive and don't plan on using this filter much longer. Even with the 2 missing screws the top seals very well and haven't had it leak. I have had 2 instances where a turtle got a leg stuck in the intake. Both turtles survived. I placed a piece of coarse foam over the strainer to prevent feet and legs from entering the powerful suction. I clean this filter about every 3 months and honestly could go twice that long with 5 turtles in the tank. I still do my weekly 25% water changes and the highest I've ever had (this was after being gone for 3 weeks without water changes) was ammonia 0, nitrite 0 nitrate 20. The media capacity of this filter if used wisely will be more than enough to remove waste from the water. My turtles are able to swim against the flow with no problems at all. The gasket that seals the pump motor to the can came unseated and leaked. I was able to use some food grade o ring lube and put it back without issue.
Overall I'm very pleased with the FX5. My turtles wouldn't have gotten stuck in the intake if I didn't change it to pvc and left it as is. I would advise anyone owning this should have a new set of gaskets on hand at all times and replace them yearly. You can't find parts in most stores for this filter so having spares on hand is a must. You won't need them if you have them but if you don't have them you will need them. The valves supplied with the filter exceeded my expectations. Most canisters I've had will leak even when they are closed but the FX5 do not. A HUGE negative to this filter is cost. Starting between $350-$400 new is a bit steep but this is truly a unique canister. For the size it is dead quiet. I have this in my bedroom and my marineland C-160 makes more noise on another tank than this does. The air purging is another great feature of this filter. Every 12 hours it shuts down for 2 minutes to purge itself. Sometimes this can be a bit noisy (my turtles like to blow bubbles into the intake for whatever reason) but I've never heard mine gurgle for more than a few seconds. If placing this in a stand ensure you have an opening of at least 23" tall to allow proper removal of the valves when cleaning. The drain on the bottom I found useless as I run a piece of tubing (connected to the 3rd included valve) into a bucket and let it suck air until it is mostly emptied. You can also run that same tube to any drain and leave the intake connected to perform a water change and connect the intake to a water supply to fill the tank back up. These are my personal experiences with this filter. I would highly recommend it to anyone wanting an excellent filter for their turtle habitat.
I can't believe you only clean it once every 3 months? You clean the outer filters weekly? I clean my whole filter once a month in tank water. I have to because I feed in tank. I just don't have the time to feed out of tank. What do you mean you didn't use the original parts? I know you swapped out the hose why im not sure they work just fine if you clean them .You used the strainer right? Just curious.