Thread: Draco Drum Solum 16 + Standard Bio review

I'd second what Mcwatson said.

Mine has ran since October 2019 without issue.

I also swapped to a less fine mesh (around 77 microns iirc) to reduce how often it cleans and also wish I'd gone for the 25 too.

My water clarity is really good most of the year, but does get a bit crap through summer.

I think it's the case that my pond is just overstocked, rather than it being the drums fault (given the amount of waste it can reasonably be expected to handle with such a small mesh on it).

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I have 3000 gals on my solum 25 and I wouldn't go any smaller as in the summer it cleans every 30 mins.
I am over stocked though.

My pond is 13,000 litres (including filters etc).



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Update - I've just found the drum motor has failed. I assume water ingress but I've emailed Draco.

In short it has been working flawlessly since the time of posting here and it's been on a short 45 minute clean cycle so more than the normal load I suspect.

My Draco drum now also has two modifications - one is a 2" hose connector for a UVC line and pump, the other is a 1" internal 90 bend that acts like an overflow to stop any rain water or main pond level rising to the point it overflows.
It's this overflow that (with the drum not turning) caused the water level to drop about an inch in the pond signalling a problem. It's designed not to drop more so at that point the water circulation is driven by the main bottom drain air.

EDIT: There is an official Draco external drum motor here (along with replacement drum seals): conversion-options.html but at that price I felt I could do something DIY and save money.

So I've got the drum working again.

The stepper motor and 19:1 gearbox were complete full of condensation and the stepper motor rotor has seized solid against the coils. The gearbox wasn't much better giving a nice crunchy sound.

I designed an external unit using a 40:1 90deg gearbox worm drive using the same NEMA17 stepper inside a waterproof electrical housing. It reuses some of the plastics, brass drive shaft, ceramic bearing, the small cog the cable gland and the cable itself.
The new box assembly is mounted outside of the Draco just next to the water solenoid and pipe work. Although I loose the 'clutch' I've never seen it bind or have a problem requiring it's use.

This draco is a 'stepper motor' variant possibly later Dracos had their stepper replaced with a motor but I can't be sure on that. A stepper has some better qualities but isn't compatible with a motor electronics. A stepper works by having two coils that it pulses to rotate the shaft a 'step' which if you look in the next photo is one of the little notches of the rotor. The original motor runs 19:1 reduction, so it rotates 19 times for each small cog rotation and then the small cog has a larger number of rotations to turn the large toothed drum.
The small box that the stepper attached to (that's the one on the side of the draco) has a small stepper motor driver electronic chip and allows you to adjust the speed in steps per second. This means for my 40:1 (ie requires twice the number of stepper rotations per cog rotation) I can increase the speed (number of steps per second) by just rotating an adjustment pot with a screwdriver) to compensate. This helps keep the drum flush cleaning the drum rather than 1/2 the drum due to the slower gearbox.

Old motor corroded and seized:
IMG_4071.jpeg

New motor position, you can see the new stepper and the 90 degree gearbox with the brass shaft and cog attached:
IMG_4151 2.jpg

Close up of the new assembly:
IMG_4173.jpg

I've shown above the shaft and cog without having the ceramic bearing in place. The old plastics are used to space the shaft and box, to support the ceramic bearing and the shaft to keep the cog engaged with the drum teeth. The screws you see are go through the plastics, through the side of the drum and into the stepper gearbox itself. The resulting assembly clamps the gearbox to the side wall of the draco.

Lastly a small notch is needed in the draco lid as the box sits above the top of the draco, This is deliberate so that the stepper sits above the gearbox and any chance of water ingress, if it gets past the numerous points the water should exit if it follows along the shaft.

I'll upload a video later today to YouTube and linked it here to show its operation. The pond seems clearer again as there system is now removing fines. When the weather is better I'll give the pond a good scrubbing and the drum will remove the remaining debris.