I'm wondering whether using an electronic pump allowing for variable flow would make sense. It could be programmed to work at maximum flow during the light time of the photoperiod and at a reduced flow when the screen is not lighted. The reduced flow, besides saving energy, would reduce the waterfall noise. I'm about to install my new scrubber and noise could be an issue.
If you utilize a 'tuned' drain, this virtually eliminates any gurgling sounds, and unless you really crank up the flow, there usually isn't much for waterfall sounds with an enclosed scrubber box. With the tuned drain, if you change the flow by reducing it, the drain might start to make noise unless you reduce the flow just right. FWIW I run my lights 24/7 on one scrubber, so I don't ever want to vary the flow on a daily cycle.
Thank's a lot for your reply. Whats is a tuned drain? This is my scrubber. It is just missing the heat sinks with the LEDs which go in the lateral positions, at both sides of the central compartment where the pipe with the screen is placed.
OK. I guess that a "tuned" drain has a valve in the drain that you can open or close to regulate the flow. I could implement that in both of my drains. Anyway, the gurgling noises were produced while testing the scrubber with fresh water. May be salt water would reduce the turbulences and the gurgling.
Nope, the SW will not eliminate the gurling, that's just a gravity-drain effect. When you submerge a drain, it increases the flow because it creates a partial siphon. It's only partial because the water falls through the drain faster than the water can fill up the pipe, so air gets in there and slows it down and it balances out. If you A) put enough water down the drain, air can't intrude and it turns into a full siphon or B) add a valve to the drain and choke the flow back, you hit a balance point where water in = water out and air doesn't get sucked into the drain. The latter is called a "tuned siphon", it's what is used on a BeanAnimal Silent and Failsafe overflow, but it also applies here. However with 2 bottom drains, this makes it more complex. You would have to valve back both, but you can do it just the same. Try this: mount your scrubber over a sink and plug one of the drains. Leave the other one submerged so it siphons. Run up the system so that you have a lot of water flowing through it. Now remove the drain pipe so that your bulkhead is above water (i.e. there is an air gap). What will happen is your scrubber will fill up with water. The siphon mean you can turn a drain that normally can't handle a lot of flow into one that can. The SM100 was notorious for being noisy, that was because in order to get it to drain, you had to submerge the pipe and turn the drain into a siphon. But the drain was generally more powerful than the inflow, so it would suck air and make bubbles, which got less of an issue as algae filled in the screen, but when the screen was clean is was loud as heck with the lid off. I solved this by adding an emergency drain and tuning the main drain. Tuning a siphon without an secondary drain is dangerous, you're asking for an overflow. Even with the Rev 1, 2, and 3, I've still heard from people overflowing their units. But that's usually after letting it grow for 1-2 months without cleaning
Thanks a lot for a great explanation. I'll do the experiment and check the siphon. As you say, regulating both valves may be tricky. Anyway I'll try it. Otherwise I may close one of the drains and regulate the other one with the valve, even though that would increase the risk of overflow. However, your latest version has the two drains at the bottom. You mentioned something about a trick you figured out to make the scrubber silent.....
Take a closer look - there is an internal divider in the bottom of the growth chamber, and the false bottom sits off to one side. Essentially I created an overflow chamber, the secondary drain will typically get little to zero flow.
That's very right. Your design will force most of the flow through one of the drains and keep the other one as a kind of emergency drain. I could do something similar in my scrubber by glueing a piece of acrylic in the inner chamber. That would make it easier to tune the flow, by means of a ball valve, through the main drain. Anyway it will not work as well, as for that the "emergency drain" should be very close to one end. Alternately, I could raise one of the drains inside the inner box, and that would make it for an emergency drain. That would be easy, just placing several gaskets one on top of the other. I'll try first to fine tune the drains by means of the two ball valves and if that doesn't work I'll try the second option.
If you don't use a false bottom, yes you could do that. But that would reduce screen area a bit, and still could get algae going down the drain. In reality, drains rarely clog up with algae from the growth. I've never has a chunk detach and block the drain in a sudden event, and I've been running them for nearly 4-1/2 years.
I agree with you in the reduction of screen area. And may be we behave a little paranoic with respect to the drain clogging threat. The problem is that if it really happens consequences (scrubber overflow, LEDs covered by salt water, light goes off, etc.) would be terrible. Thanks for all the help and comments
