4ft River tank with too much back flow :- like a whirlpool

[mattyd]

Hi all.

Since I first saw a hillstream loach a few months ago at my local bulk goods pet store I have fallen in love with the idea of creating a River tank for their specific display/keeping.

I have a 4ft tank, 18x18 high and wide. I've made a under-substrate manifold using2x 3.5ft lengths of 25mm plumbing PVC pipe, with 2 intake sponges connected at one end, and 2 power heads at the other.

I filled it up for the first time last night, and now I'm wishing that I had have trialed it all before putting my DIY planted tank substrate and then gravel/sand in.

When I turn on one pump, it starts sucking water through the adjasent pump, as well as the two filters at the other end. But the water flow is so strong that it blasts water in a massive circle around the tank.

When I turn the other pump on, the problem gets worse.

What I was hoping to see was most of the water get sucked into the sponges, and the water only flow in the one direction.

My intakes are the sponge assemblies from the large internal filters. The power heads are the the pump assemblies from the same large internal filters. They all match the pipe work perfectly, but clearly the sponges aren't adequate at handling the high rate of flow that the pumps can output.

So, my question to my fellow internet River-tankers is this.... what have I done wrong?
1. Do i need more pipes going the length of the tank to help with flow?
2. Do I need more intake points? More sponges on extra risers?
3. Do my existing sponge intakes restrict the flow due to the plastic surrounds, etc?

I bought 6 Gastromyzons last night, and they are temporarily being kept in a 12x12 inch tank that is very mature and very covered in lovely thick algae... so they are happily in a good place, albeit there is no flow in that tank with the only filtration and water movement being provided by a very very small powerhead that is blowing water down one side creating an inch of raised water/wave that the little fellas love playing in.

I have pics, but I'm not sure how to load them.

Matt

[Diana]

It does sound like more intake points would help. What happens if you remove the sponges? Less restriction on the intakes you have? If this helps, then maybe use a coarser sponge. Next would be to dig up that end and double the intakes.

There will be some swirling in almost any river tank set up, but such strong water movement to describe it as a whirlpool is too much. Mine has a bit of a swirl at the top, but I can follow food as it sinks and the food drops an inch or less into the water in the swirling pattern, then shoots across the tank in the direction the river is flowing.

[mattyd]

I've got some plant off-cuts floating in the top of the tank at the moment, and they'll go from one end to the other in the correct direction in the space of 2-3 seconds, and then move to the back of the tank and return to the powerheads in about 3-5 seconds. The ambulia will get caught by the flow as they float lower in the water column and will even race around the sponges before returning. The dwarf val just seems to sit in the middle turning on an axis as they bunch up and get pulled by the flow at the front and pushed by the flow at the back.

I'd love to throw my Giant Danios in there... I think they'd have an absolute blast, although they would probably get tired and exhausted after a while with no where still to rest.

But yeah, I think I'll have to pull out the temporary water storage containers tonight and drain the tank and then dig up the manifold and add in another 2-3 points for water return. Maybe even add in another 1 or 2 return pipes. It didn't seem to make much difference when I took the sponges off the intake tubes. I could feel the suction but it didn't seem as much as what the pump was putting out.

I might also have to make sure that the pumps are sealing into the pipework properly.... it would be just my luck that they are sucking in water from the tank from where they shouldn't be!

[andyroo]

It's a river-tank, so set some refugia points: eddies around flower-pots, rocks, flowing plants, upright flat stone, bamboo/PVC pipes etc... and let 'er rip.

There are a couple of how-to postings on this list about posting photos, maybe in the "stickies". Let's have a look.
A

[Diana]

As Andy notes, even in a real river there are calm areas around rocks and driftwood, so if you have similar things in your tank the fish can swim in the current when they want and take a break when they want.

Good idea to check that the powerheads are not getting too much of their intake from that end. If you do not want to glue them (I did not glue anything) some fittings can sealed better with some vinyl tubing.

[mattyd]

I took the water out last night, and then all the stones, and the plants, but didn't get enough time to dig up the substrate carefully enough to keep the gravel, sand and dirt all separate.

The problem I had was that there was absolutely no area in the tank that had low or no flow. Everything was rushing around with the water.

I'll be increasing the intake number and general manifold volume in a few days, and getting some vinyl tubing just in case I can use that to achieve a better seal between the powerheads and the manifold.

For now, I have nothing further to add.... except that it looked awesome last night before I started draining it.

I'll post some picture shortly.

Matt

[mattyd]

Okay, I finally worked out how to upload pics to my website (that I haven't done anything to since registering it almost a full year ago! Someday I'll put all my knowledge about hifi systems, amps and wiring home theater into it for everyone else to use). Now that I have pics on it, I can show you what I've been up to.

Now, since I lost posted I have basically just let the fish tank sit empty. I lost all but one of my gastromyzons to white spot in a small planted tank and the associated accidental overheating when I turned the temp up on the heater but forgot to check it for 4 hours (it hit 33deg for a few hours before i noticed).

Here is what I had that I was complaining about earlier:
These are the bottom of two internal filters I had. I found some electrical conduit was perfect size to fit into them, so I had to bulk out the pipe with a bit of black silicon to mate it to the plumbing PVC I had bought.


This is power heads that I had plumbed in.


With the dirt, sand, gravel and pebbles loaded in, and half a tank of water this is what it looked like. You can see that there was a fair amount of surface agitation, and that bunch of plants in front of the powerheads is actually rotating on the spot. The dwarf val I've got planted at the middle back is actually being pushed by the water back towards the power heads.


I decided that these filters weren't able to cope with sucking enough water through all that plastic.



I really liked the look of it:


I especially like this sort of look. But as you can see the dwarf val at the back was kinda getting pushed around a bit in the wrong direction. And I wasn't happy with that.



So, I decided I needed something that was better at sucking water back from the left of the tank through the manifold back to the powerheads. So I got out my drill and an 8mm drill bit, and the PVC pipe, and started again. I drilled so many holes, and managed to put two holes in my left index finger and thumb. Then I built up a simple little jig with some scrap wood. That saved me hurting my finger again.

This was the first....


2 done.


I decided originally to do 6. Thinking that even though it would look ugly, it should be able to fully suck down as much water as necessary, and do it slowly enough through each sponge that the filtration capabilitly would eb better. Once I did a few dry runs on the carpet in front of the TV, I realised that 6 would look too crowded and be too much effort, so I just stopped with 5 (although I drilled up the 6th one... talk about taking forever.... I think each pipe took about 2 hours to drill).

Then I bought a background 2nd hand for $50 AUD (you can see it being proped up with the little garden trowel and filter cone).


If you look at the pipework, it is now using 3 long pieces. Each long piece has a sponge on T join, with a larger diameter t join connected on the other side. Using these larger bends and t joins meant that there was a larger internal cross section for less eddies and increased water flow (I assume). None of them are glued.... I have just whacked them together. After all, I don't really care if water leaks in or out as it is going to be under a substrate. There are no gaps big enough for dirt or sand to get into.


At the powerhead end I am using the same power heads. I think one is 2200 lph, and the other is 1800 lph. I found that the clear vinyl tubing fitting perfectly snuggly over the outside of both inputs. And that same tubing also fitted (but more snuggly) over the ends of the larger PVC elbows. I think those elbows are for 30mm piping. I think.... (my memory is never too crash hot, and I'm sitting at work so I can't check).



This morning I dug out the gravel, sand and dirt from the back. For those of you with hillstream loaches (sewellia, gastromozyons), do you think I should make sure that the background is completely sealed to the backwall? Should I make sure that there are absoluletly no gaps at all for any fish to get in behind the moulded 3d latex rubber backing? If I should be worried about them getting in behind then I can be really pedantic and fully silicon it to the back.

So, should I stick the backing on with out a single gap?

I'm not going to worry about any backflow once I get it ready for water. If there is the same large eddie of water going back the other direction then I'll just put some other big rocks in that area for the little fish to cling to.

Matt

[avant]

The modified setup is looking awesome!

I would definitely advise sticking the backdrop to the glass wall. It is almost definite that the loaches will find their way behind it.

[Diana]

That looks like it will really help. Now that I see the pictures, I do agree that the original sponges may have been too fine, and too much hidden in plastic. Really restricted the flow, even through they seem to have a large area.

Looking forward to seeing how this version works.

Yes, seal the background to the back of the tank.

[mattyd]

Well, this is what the tank looked like a few weeks ago:




I originally had 10 or 11 gastomyzon hillstream loaches. However I think I only have 5 left now. I know two of them died from injuries and stress due to poor catching methods at the store (one of them developed a massive bump on its back), and two others seemed to have their skin peel off (not sure what disease it was, but I pulled those two fish out for quaranteen (they both died), dropped the water level and used some methyl blue stuff for 3 days at a time and didn't lose any others). The last few deaths I believe are due to poor health from either starvation or death from the blotchy skin color disease.

This is the large gastromyzon I have left with the faded color. I have just posted a query in the Health sub-forum to see if anyone in the USA can help me out by buying some meds and posting them to me in Australia. I really do not have much here in Aussie land to help these guys combat the infection that causes their bad skin color.



I also bought 4 homoloptera 'lizard fish'. I have no idea which species they are, of even if they are the same species because their skin changes color depending on what they are sitting on.
It is great fun to feed them live black worms straight out of the pipette, or by tipping in a defrosted cube of blood worms.







The tank has about 20 something zebra, long fin zebra, albino zebra, leopard and albino leopard danios as well.

I did a water change two nights ago about 30mins before dark and modified the flow of the tank and the airation in the tank. The tank was heating to 28deg with both powerheads going, so I turned off one (and blocked the outlets), and added a venturi airpipe to the other. This is what it now looks like.



With the water change the temp dropped 5 degrees and I filled the tank to to top. I woke up early the next morning and the danios had spawned everywhere around the sponges and algae (but the eggs got eaten fairly quickly). I will be trying to breed them in proper spawning tanks in a few months when I get the tanks set up.

Here are two of my little hillstream loaches enjoying the extra bubbly and colder water. I wish I knew a better food source to feed them that wouldn't get blown away by the flow.

[wimvanvelzen]

hi Matt,

Beautifull setup! I am sure your hillstreams love it.
I would add some large boulders and pieces of wood though to form places with relatively little flow.