What do flow meters do

Contribution from Ramirezi »

Certainly each of us has asked for a possibility several times to be able to determine any flow rate with some degree of certainty!

For example, when determining the amount that the return pump actually creates from the technical basin up into the aquarium.

Often enough lifting heights of> 1.5m have to be overcome here. The performance diagrams supplied give you an idea of ​​how to set the pump - but unfortunately experience shows that this cannot be more than a vague clue!

Every bend, every 45 °, and even more so every 90 ° angle in the piping results in drastic deviations from this theoretical maximum value!

So if you just choose a clear “loss surcharge” as a precaution, in the worst case you will bring significantly too much energy (via the pump motor) into the pool, which then simply turns out to be not only useless as heat energy evaporates, but also drives the pool temperature up - for nothing and again for nothing.

Another absolutely important aspect is the effective work of the protein skimmer. You just have to keep in mind that the modern skimmers in our technical basins only work in bypass mode. So if such a water hurricane rushes through our TB, then the AS gets very little water per unit of time. On the one hand, this drastically lowers the efficiency, and on the other hand, water is simply scooped around pointlessly - so for nothing and again for nothing!

Jörg Kokott discusses these relationships in detail in his “Sangokai Recommendations A-Z” in the area “E” for “Effective flow volume”.

The methods mentioned there for gauging using a bucket and subsequent extrapolation to the final value were, not least because of the expected susceptibility to errors, simply too much water splashing, and therefore clearly too time-consuming.

So what do you do then? - One thinks about alternative possibilities!

Enough of the preface, let's get to the heart of the matter:

Why not check a Gardena water meter (which was lying around in my garden accessories) for its usability?

This is what this thing looks like in the original.

Gardena water meter Original.jpg

Said and done:

- The part is inexpensive (does not cost 25.00 euros),
- is nice and small,
- Lo and behold, it can determine flow rates in l / min!
- (And that can be switched between gallons and liters.
- So could even be used for our friends from the Anglo-American language area)
- The measuring range is 2 to 30l / min, and thus 120 to 1800l / h.
- So more than enough for our purposes!
- The measurement error to be expected is specified in the data sheet with ± 5%, but at least with ± 0.5 liters.
- That is not a big deal for us either, and it is certainly still orders of magnitude more precise than the bucket method.

I want to briefly anticipate the instructions and present the finished part here after the conversion:

Gardena ready for use.jpg

As you can see: It is not even time consuming!

On the contrary, the work required is absolutely simple and only requires a small portion of manual skill.
All in all, maybe an hour of work!

The water inlet can be seen at the top of the picture, the exit at the bottom of the picture.

What should I do? Well - basically only two things, namely adapting the water inlet and outlet to our purposes.
In doing so, you are guided by your personal ideas:

- Do I need an adapter for different connection options?
- If so, then I'll build a pipe / socket combination like the one in the picture above,
and am therefore flexibly equipped for all measurement tasks.
- If not, then just a short piece of pipe is enough to attach to the outlet in the pool.
- The same considerations apply to the lower adapter:
- This version would now be suitable, for example, for inserting in between, if one should use such an "outlet nozzle" at the outlet into the basin:

outlet nozzle.jpg

If you don't need that either, you can simply leave out the screwed-on Gardena hose coupling - the bottom line is that it makes even less work!

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VG, Udo

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