Python question / debate

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One thing I do is run very hot water through the python for several minutes before switching tanks. It's not going to kill bacteria, but I doubt that algae and parasites will enjoy it much.
pkillur said:
Yeah. So, in theory I have a 360 gph pump on my Fluval 404 with max head of 6 ft, so probably the flow is cut in half for the threeish feet it goes up and into my tank. So, at 180 gph (in a perfect world) it takes 25 minutes to disolve all the chloramines. This is all in a perfect world with perfect flow, etc though. I suppose it's not too bad...

To be honest you're getting more than 180 gph. I'm an engineering nerd, and I deal with pumps and pump curves all of the time. You're probably getting somewhere near 85-90% of your max flow I would guess. You can't really tell that without looking at the curve, but with the way curves are shaped for a centrifugal pump that is probably a moderately accurate estimate.

Also, you have to figure that the flow stirs up the rest of the water too. Just like how it's possible to blow up a trash bag with one breath (of course it depends on the size trash bag :)). You move the trash bag away from your mouth about 1.5 feet and blow. The air that comes out of your lungs makes more air move into the bag. This is sort of the same theory. If you put a few drops of food coloring in your tank (in front of a water flow), I'm sure you'd see it fill the tank uniformly within about 20-30 seconds tops.
dont155 said:
For the Python syphoning issue, I discovered quite by accident that I could in fact, increase the suction a bit. The "problem" was literally at the tap. The part that goes on the water spicket isn't supposed to be "rotatable". That is, when mounted, the part should not easily rotate to accomodate the direction the hose is coming from. If it does, then its loose and is leaking air which, of course, reduces the suction. You need to tighten it up so it doesn't spin.

Nice tip! Thanks!
JRagg, the loss of flow isn't as much about the reduced flow through the curved hose as it is the fact that he is lifting the water in the tube. If the source water is lower, water wants to siphon out of the tank so the pump is working against it. Check out this link . Look at the RIO 800HP. With no rise it pumps 211 gph, but at three feet of rise its down to 100. The larger the pump, the less percentage loss. Add in the curve and figuring for 50% of max is not unreasonable.
I have three tanks setup and I have used the python for years. I know if I had to use buckets to do water changes I wouldn't be doing as many. I do the tanks once or twice a week and gravel vac some of the gravel each time. My tanks and fish are healthier and it is much easier to do. If I worked in a lfs I'd rather sell someone a python and some prime and know that they will be doing pwc's than not doing as many pwc's and the customer ending up with unhealthy fish.
When I was saying the word curve I meant the pump curve. You can draw one based on the data points on that table that you looked at. Here is a page that talks a little bit about pump curves. The drawing there is pretty poor, but it gets the point across.

His particular pump would be closer to the RIO 1100 than the 800. It has the same shutoff head and close to the same runout flow.

That particular one gets about 62% of its max flow in pkillur's case. Adding in any head loss could possibly take it below 50%

I guess I'm used to dealing with much larger pumps. The larger ones on that site support what I had said earlier.

In any case, the second paragraph of what I had said still holds. With all of the flow created by the filter pump, it would not take long for the dechlorinator to be evenly spread around the tank. Doesn't have to go through the pump to make it mix. It's the flow and turbulence in the water created by the pump that matters.
These pump curves don't apply to canister filters because canister filters do not have to fight gravity. The water level in the tubes is automatically level with the tank and the weight in the out tube is offset by the weight of the in tube.

I think

The pump curves still apply (they should always apply), but the 3 foot head doesn't.

The backpressure is still greater than zero, but that definitely increases the flow some.
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