Filter Is Too Strong

[squidneh]

So, I got a sunsun submersible filter quite some time ago and just got to installing it.  Well...it is way too strong.  It is the JP 025f model, about 420gph.  My tank is a 75 gallon.  
 
I purchased the filter because I previously had two that would have been insufficient should the other be taken out.  I wanted better circulation and the ability to add more media.  But... my neons, tiger barbs, and gourami are all fighting to not get sucked towards the filter, then getting swept back by the output.  I don't think they would get sucked in as they are not ill or injured, but they are constantly swimming against the intake current, then getting pushed back out by the output, so on and so on.  And my gourami is about 4 inches.
 
What are my options for baffling both the intake and output?  I think I'm going to add some denser media, but I've never had the problem of a filter being too strong before, always the opposite, so I'm at a loss.  To add to it, this is my first internal filter experience.

 

[Akasha72]

Can you fit a spray bar to it perhaps? That would help calm the outward flow. The only other thing I can think of is a pair of stockings (do you call them panty hose still in the States? We call them tights or stockings here in the U.K) I have encased an entire internal filter in a stocking before when I've had young fry that needed a gentle flow

 

[Byron]

You are quite right to be concerned.  Fish that are designed, as the species named are, to live in still (gourami in particular) or at most mild-flowing streams (and they tend to remain near the stream banks where there is less flow than in the main channel) will literally wear themselves out if forced to battle a strong current.  And the filter is on 24/7 so they get no respite at all.  It takes considerable energy for the fish to maintain itself, and this means other functions are being ignored, contributing to poorer health overall.
 
Aside from changing filters, there are some options.  First is that some filters have flow controls; not sure about the one you mention, but it might.  One  option is to aim the filter return directly into an end wall.  The filter can be placed along the back and in from that end wall which will lessen the current a bit more than if it is right in the corner.  The force is against the wall where it spreads out and then moves down the tank at an easier rate.  If this is still significant, a large chunk of wood or rock placed somewhere in the flow from the filter will spread it out.  Some will suggest baffling the filter return with filter foam or similar, but be careful this does not impede the operation of the filter to the extent that it causes damage; filters are made to operate at the specified rate and blocking this artificially could cause damage.
 
As for the intake to the filter, I would use wood or rock around this, close to it.  In addition, if fish were actually being pulled in, screening can be placed around the intake, but this will not lessen the draw but only prevent fish being pulled in.
 
Byron.

 

[squidneh]

Thank you both.
 
Akasha72 -we call them pantyhose or nylons in the US, at least where I am from.  But I'm familiar with the term stockings as well thanks to the internet  The spray bar is a good suggestion and I will see if I can find one reasonably priced or create my own.
 
Byron, as always great and helpful advice.  My gourami is my main cause for concern as you stated, but even the other fish that may not mind a current are struggling (should say were, as I have shut that filter off for now until I can fix it.)  I will see if moving it to a different location/angle will help reduce the flow as well, as that would be a more immediate solution. 

 

[TwoTankAmin]

Blocking a filter output will not cause damage to the filter. It may cause it to overflow or to flow around, but it will not harm the pumping mechanism. Blocking intakes will definitely cause damage over time.
 
Consider a pump. It has a specified flow rate at 0 height, Then you can see a chart of flow rate vs head. At a given height the flow will stop entirely. This is because the pump cannot lift any more weight of water in the outflow hose. Now, if it were harmful to block the output side, lifting water would mean breaking it, but is does not.
 
I return water to tanks using pumps and garden type hoses. I have a ball valve on the output end to adjust or stop the flow. I turn off the flow all the time and the pump is pushing against that closed valve, often for hours. My first return pump lasted almost a decade, it did not break, The power cable began to fray where it entered the pump and this caused me to replace it.
 
This is also one reason one needs to rinse prefilters regularly and the same is especially true for powerhead driven sponge filters.