Flow Rate Too High?

[David J]

Hi all,

I'm looking for some advice on the flow rate of the water in my tank since installing a new fluval 206 external filter to replace my U2 internal.

My tank has been cycled since February and i have been stocking gradually starting with lemon tetra then glowlight tetra and most recently, panda corys. It was always my intention to switch to an external once I got to around thus level of stocking before adding any more in order to better deal with the bio load.

A couple of days ago I installed the new filter along with a spray bar. I have the spray bar on the left side, flowing across the width of the tank left to right. In order to make it fit I had to shorten the bar. There were 3 holes on the part I sawed off. Once it was installed and switched on I immediately noticed the stronger flow rate of the water and worried that it might be too strong for the fish. I decided to monitor them and after a day I felt it needed to be reduced. Fluval say you can reduce the flow by raising the aqua stop lever upto 50%. I tried this and it certainly reduced the flow but not enough in my opinion so after some reading online I decided to drill and extra hole and widen the existing holes (one drill bit size above what they were).

This reduced the flow to what I feel is more comfortable for the fish. Then, last night, I found a lemon tetra dead. I count them regularly so it must've died in the last couple of hours. As far as I could tell, all my fish have been healthy before this. The dead lemon looked fine, apart from being dead. I couldn't see anything obvious wrong. I posted last night in the emergencies section and the feeling was that it probably wasn't related to the higher flow. Oh, forgot to say that I am currently running bother the new filter and the internal until I was sure the new one was running ok. Once I was sure it was working I was then going to put the mature media in the canister.

So last night I decided to turn off the external and just run the internal until I considered what could have caused the lemon to die. 24 hours later, no more dead fish and I have now switched the external back on.

Below is a link to a short 2 min video of the tank tonight with the external running and I wonder if some of you would mind taking a look and give me your honest opinion on the flow rate. I am also bearing in kind the fact that the internal is adding to the flow and it will be coming out after a couple of days but it doesn't create much current really. Please let me know if you think the fish seem happy enough.

Please could you also comment of the position of the spray bar. You will see that I have the end at the front rised to the surface opposed to the back end which is about an inch under the surface. The reason I did this was to create bubbles to get more oxygen into the water. I have heard many different views on whether you need this. Some say a rippled, unbroken surface is fine. Others say you need to break the surface. I'm confused.

Thanks for reading. I just want to get it right. I'm gutted about losing the lemon last night. They were the first fish in the tank and it was one of the big males which had really beautiful striking colours.

Here's the video, I hope you can access it. I uploaded it to photobucket via my ipad.

[media]http/i639.photobucket.com/albums/uu120/DavMars/IMG_0294.mp4[/media]

Thanks,

David,

 

[Livewire88]

Looking at the video the flow looks fine to me, definitely not to much IMO. Also the spray bar placement looks fine, the surface of the water is being disturbed sufficiently. 
 
I would put the death of the Tetra down to coincidence 

 

[David J]

Thanks Livewire, what about the oxygen? Does it look like the spraybar is position ok? Do I need bubbles or not? Tonight I've noticed twice a lemon rushing to the surface as if to get air and then rush back down. I can't say I've noticed this before.

 

[Livewire88]

You don't need bubbles, as long as the surface is being agitated your fish will be fine. You could even move the end that is higher causing the surface to break down a bit if you like. 
 
Also your intake pipe position is fine but if you wanted you could put it on the same side as the spray bar, this way the spray bar will push the water across the top of the tank, deflect down and back to the same side as the spray bar, so if the intake pipe was also on that side it would create a nice circle of flow. 
 
Nice looking tank BTW 

 

[David J]

Thanks for the compliment. The tank is a bit messy at the moment. Tuesday night is clean up night lol.

I see what you mean about moving the intake to the left but I can't because the tank has little half moon cut outs for cables etc to fit through. I used those to sit the U Pieces for the hoses but had to cut the lid to allow them to fit properly. Basically this means they have to be where they currently are unless I do more mods.

I will try different heights for the spray bar and see what I like. What do you think about the lemons rushing to the top?

 

[eaglesaquarium]

There's a lot of reasons a fish would do that.  Occasionally mine will think that they see food there (just a bubble that didn't burst right away) and dart up.  I don't think its a big deal, unless you see them starting to hang out at the top consistently.  
 
 
 
Looks good David!

 

[David J]

Cheers Eagle. They seem to have settled into the new flow. I guess I need to give it time to gain confident of the new equipment.

I had a mini disaster when I first switched it on when water started pumping out of the side. About 8 litres of water ended up on my floor before I stopped panicking and shut it off. After spending the next half hour dealing with the water I found out why. I hadn't put the rubber seal in properly. I had it round the wrong part in the lid section and there was a gap between the top and bottom sections when I had it clipped shut. I moved the seal to another groove and then there was only a gap of about 1mm and it doesn't leak when I turn it on.

I'm still slightly worried about it leaking because when I turned it on and ran it for a while I thought it was louder than it should be. I'd heard people saying it was near silent. I can hear a definate hum and there might be a slight rattle noise. I emailed the supplier and they said it was air trapped in the system and that I should turn the filter upside down while it is running and to then gradually turn it back upright a bit at a time and this will disperse the air. I was worried that it would leak badly if I did this but he said as long as I have the hoses in the tank it wouldn't leak. I tried it and once I turned it to about 45 degrees it leaked so I didn't go any further. I could hear air being dispersed but I don't think I got it all. I gave the filter a shake and more air moved. I think it is a bit quieter but I'm paranoid about it leaking because I know it's not water tight.

Does anyone know if it should be airtight and not leak at all if I turned it upside down?

 

[Livewire88]

The filter should not leak at all, so it sounds like the seal is not seated correctly. 
 
I would take the lid off and make sure the seal is straight when you fit the lid back on, make sure the lid is square with the canister so when you push it on the seal stays straight, you can even use a little bit of Vaseline spread on the rubber seal to help it seal correctly. 

 

[David J]

I'll check it tomorrow night after work. Do you think it'll be ok until then? It's running and definitely not leaking.

 

[Livewire88]

Should be fine, just don't turn it upside down...

 

[David J]

Hi again,

Been worried all day while t work, expecting to come home to a disaster but no. Everything seems fine. No losses and everything looks happy and no leaks. I did a 25% water change tonight. I haven't had time to check the seal but I will be doing another water change in a couple of days so will check it then. I am also hoping to remove the internal and put the mature media into the new filter.

Anyone got any tips on what to do with the media? Where to put it exactly. Do I put everything over or just the bio or just the sponges?

Thanks,

David

 

[eaglesaquarium]

I'd put the mature stuff as the first element in the external, but its going to be up to you what fits best.  Ultimately, its about what you can do.  I'm not familiar with your particular filters, so I can't give more specific advice.

 

[David J]

On the left, the first stage of filtration is 3 sponges totalling about 2 inches thick. Those take up the entire left side of the canister. The right hand side has 3 drawers. The bottom one contains another sponge for finer debris. The middle section has the biomax and the top section has carbon.

I'm thinking I should put the sponges where the sponges are and mix the biomax in with the new biomax.

 

[eaglesaquarium]

Sounds good to me.

 

[David J]

Cool. Sounds kinda obvious but I wondered if there might be a knack to it such as put everything in the first stage for a week then move some to the next and so on.