MP40 waves

[FrootStick]

Hey guys

So I have 2 MP40's on my 90g tank.
I have an apex also and was hoping to be able to set these up to have a wave at some time during the day.
What's my best placement to get this happening and what setting should I run?
I've been having a bit of a play around today, but can't get it going.

Any ideas guys?
Thanks

 

[KorL]

I like to have them just below the water line about 6-8" or so where it's not pulling air from the surface.

 

[saltyhog]

I have two MP40's on opposite ends of a 6' tank and get a nice wave with short pulse mode in synch/antisynch configuration. You have to tweak the pulse length depending on the dimensions of the tank until you get the best wave. You can also store that wave and implement it in other modes such as Nutrient Transport (I believe that's the one)

 

[FrootStick]

Should I have my pumps facing each other or offset?
I've had it on pulse mode but don't seem to get the desired affect.
I've adjusted pulse times and everything through the apex with no luck.

 

[saltyhog]

Mine are offset You have to give it a minute or so, then adjust till you get the best wave.

 

[FrootStick]

Yeah mine are offset to. I was trying all day yesterday with no luck different plus times. On anti sync.

 

[nervousmonkey]

You won't find a specific time to set for your tank to resonate, as each tank is unique. Creating a wave in the tank is a function of length, height and width, with no particular order for one vs. another. You could theoretically solve an equation to calculate the resonant frequency of your tank, but there are too many variables to consider the calculated values vs. finding the actual values (Rock placement, etc.). It is important to point out, however, that standing waves in an aquarium create a lot of stress for an aquarium and will definitely shorten their lives.
That being said, you can figure out your tanks resonant frequency by knowing the dimensions (what are they by the way?) and using that to compare against published figures for aquaria, but that'll just get you in the ballpark and you will have to keep experimenting. For example, I use two WAV's on one of my tanks (40 G frag tank), and I know the resonant frequency of that tank, so I can create multiple types of standing waves as long as I set the frequency, or time in seconds, as a multiple of 0.25s. If you want to calculate your tanks resonant frequency, use this equation where f is the resonant frequency: f=c/2*(square root of {inverse(x squared) + inverse (y squared) + inverse (z squared)}, where c=1500 m/s and x, y, and z are the dimensions of the tank and the inverse function is 1/xsquared... That's more a pain than it is worth it, since you'll still need to experiment to get the wave you want, so just keep trying. FWIW, shortening a tank's lifespan for a wave isn't worth it to me, but it's cool to watch anyway.
Ecotech has information on their site about creating a wave, but no one can tell you what your tank needs to have...

 

[saltyhog]

You won't find a specific time to set for your tank to resonate, as each tank is unique. Creating a wave in the tank is a function of length, height and width, with no particular order for one vs. another. You could theoretically solve an equation to calculate the resonant frequency of your tank, but there are too many variables to consider the calculated values vs. finding the actual values (Rock placement, etc.). It is important to point out, however, that standing waves in an aquarium create a lot of stress for an aquarium and will definitely shorten their lives.
That being said, you can figure out your tanks resonant frequency by knowing the dimensions (what are they by the way?) and using that to compare against published figures for aquaria, but that'll just get you in the ballpark and you will have to keep experimenting. For example, I use two WAV's on one of my tanks (40 G frag tank), and I know the resonant frequency of that tank, so I can create multiple types of standing waves as long as I set the frequency, or time in seconds, as a multiple of 0.25s. If you want to calculate your tanks resonant frequency, use this equation where f is the resonant frequency: f=c/2*(square root of {inverse(x squared) + inverse (y squared) + inverse (z squared)}, where c=1500 m/s and x, y, and z are the dimensions of the tank and the inverse function is 1/xsquared... That's more a pain than it is worth it, since you'll still need to experiment to get the wave you want, so just keep trying. FWIW, shortening a tank's lifespan for a wave isn't worth it to me, but it's cool to watch anyway.
Ecotech has information on their site about creating a wave, but no one can tell you what your tank needs to have...

Absolutely! My "wave" looks nothing like that video, that would definitely make me worry about the longevity of my tank. I just want a nice little back and forth motion. I watch my duncan and euphyllias to see if it looks right. I also only run that wave for about an hour or so and the short portion of NTM it makes up.

 

[nervousmonkey]

HAHA! Man, the viable lifetime of the tank in that video doesn't appear to have many years left, does it?
Personally, I like having a profile set up for when people are going to come over so they can see the waves, but it really doesn't perform any particularly useful function. I do that same thing saltyhog, with duncans and hammers. They do look much more cool in a tank; at least guests can see the movement.
Using the resonant frequency of one's own tank makes powerhead placement a lot of fun; I use the WAV's on the back wall pointed up at an angle towards the front wall and can create some awesome standing waves that go from front to back, then mixed with one from side to side reminds me what it must be like for the fish during a small storm. LOL!