Apex FFM and Flow Sensors - My Impressions

[ca1ore]

I purchased the FMK back in early 2017 (as soon as it came out), and have subsequently added a couple more of the flow modules and a number of additional sensors. I see a lot of questions about this kit, so thought I'd share my impressions after 2 1/2 plus years of using them.:

1. Although I have seen some folks have issues adding the FFM to their apex, I did not. They all added just fine and have the capability to accept flow sensors, optical sensors and leak detectors.
2. The flow sensors can be quite restrictive of flow, so depending upon your application, upsizing the sensor may be prudent. On my main pump return, for example, I went with the 2" model. It is physically quite large, but it presented very little back pressure to my pump.
3. The flow sensors require regular cleaning. Debris will prevent the paddle wheels from turning, and eventually detritus buildup on the center spindle will do the same. If one of my sensors reads zero flow, I remove it and clean it. Sometimes this is just mechanical clearing of things like chaeto strands; other times you have to disassemble the sensor and clean out the spindle assembly.
4. The sensors have a min and max flow rating. Trying to run a 4,750 gph ampmaster pump though even the largest sensor is a non-starter.
5. FS200 - has been reliable for me. Have had it for two years and only needed cleaning once.
6. FS25 - also has been reliable for me. Have had it for two years and it hasn't required cleaning yet.
7. FS50 - same again. Have had it 2 1/2 years and its only needed cleaning twice. It is restrictive to flow though.
8. FS100 - the black sheep. I have a five of these and they can be quite temperamental. I have to clean them out pretty reliably every 3 months (somewhat dependent on where they are placed). The initial FS100 I got lasted about 18 months before needing to be replaced. One other, less than a year old, had the black metal ring on the paddle wheel start to disintegrate and Neptune replaced it under warranty.

I do NOT recommend using the output of the FFM to actively trigger any actions. I use mine solely to send me alerts. If the sensor on my main pump were to read zero, there are other level sensors in the sump that would also trigger if the pump itself had stopped - as opposed to a flow sensor issue. So shutting down the main pump in the event of a zero flow reading would just make a problem where one didn't exist. The majority of my flow sensor alerts (always FS100s) end up being sensor failures.

 

[SPR1968]

Very interesting write up, I’m just in the process of installing them in my new system and I’ve gone for the bigger size we’re needed, like the 2” so it doesn’t restrict the flow.

It’s a big piece of kit this one as well, especially taking into adapters to go from 32mm to 2” and back to 32mm in my case. Looks like something from the USS Alabama not a fish tank! Lol

I agree I wouldn’t want them to tell Apex to act on any of their readings other than a notification

 

[SuncrestReef]

I agree, nice write up and review.

I do want to point out one counter-argument about controlling devices based on flow. I have a 1" flow sensor measuring flow through my UV sterilizer, and if the flow drops below 100gph, the Apex turns off the UV to prevent over-exposing the water or to prevent damage to the bulb from overheating. If there's a false reading due to buildup on the flow sensor, I'd rather turn off the UV than risk damage. This has no other impact on my system. Of course I also have alerts set up to know when this happens, but I feel shutting down UV is prudent even if the sensor might be wrong.

 

[TheHarold]

I agree, nice write up and review.

I do want to point out one counter-argument about controlling devices based on flow. I have a 1" flow sensor measuring flow through my UV sterilizer, and if the flow drops below 100gph, the Apex turns off the UV to prevent over-exposing the water or to prevent damage to the bulb from overheating. If there's a false reading due to buildup on the flow sensor, I'd rather turn off the UV than risk damage. This has no other impact on my system. Of course I also have alerts set up to know when this happens, but I feel shutting down UV is prudent even if the sensor might be wrong.

Agreed- as flow sensors can really only fail reading "low" (due to the analog signal), no harm in doing that to protect non-essential equipment or send warnings. But shouldn't be used on return pumps, of course.

 

[SuncrestReef]

Agreed- as flow sensors can really only fail reading "low" (due to the analog signal), no harm in doing that to protect non-essential equipment or send warnings. But shouldn't be used on return pumps, of course.

Actually, flow sensors can fail reading "high". This happens occasionally if the FMM loses the configuration and defaults back to a 1" flow sensor. If the sensor size is not specified correctly, it can report artificially high flow rates. If you see a sudden high spike in the flow rate graph, go into your FMM configuration settings to confirm the flow sensor sizes are correct. This has happened to me twice in the past year for no reason.

And I agree about not controlling pumps due to flow readings.

 

[ca1ore]

I agree, nice write up and review.

I do want to point out one counter-argument about controlling devices based on flow. I have a 1" flow sensor measuring flow through my UV sterilizer, and if the flow drops below 100gph, the Apex turns off the UV to prevent over-exposing the water or to prevent damage to the bulb from overheating. If there's a false reading due to buildup on the flow sensor, I'd rather turn off the UV than risk damage. This has no other impact on my system. Of course I also have alerts set up to know when this happens, but I feel shutting down UV is prudent even if the sensor might be wrong.

Yes, that is an excellent observation.