# Is high flow making my fish miserable?



## Sacha (21 Nov 2014)

In my endless effort to achieve "good circulation" around the tank, I now have an obscene amount of flow. My tank is a Juwel Rio 125. I have one 1250 lph Eheim external filter, and a 1000 lph internal filter pump. Accounting for displacement, I have around 20x turnover I reckon. 

Flow is delivered via two separate spray bars, facing in the same direction (from back of tank, forwards towards front wall). 

Since upgrading from the 600 lph internal pump to the 1000 lph, the fish are hiding a lot. The cardinals seem fine with the flow, but the Pentazona barbs hide at the back of the tank, and I never even see the cory (trilineatus) anymore. When the pump is off during a water change, they all come out and are active and happy. 

Also, I lost a barb yesterday. It showed no signs of illness or old age. Can high flow actually kill fish through exhaustion? My fish seem very tired. 

So, is high flow bad for fish health? Does anyone even care? Whatever problems I've had on this forum, I've always been told to "improve my injection/ distribution regime". Well, I've definitely done that now, but I'm concerned about my livestock.


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## ian_m (21 Nov 2014)

Don't know about too much flow, but I have JBL1500 (1500l/hr) Juwel internal (600l/hr) and Hydor 3200 (3200l/hr) total 5300l/hr in a 180l tank on 24/7, plants move & fish swim. They don't seem particularly bothered, they do seem to find gentle spots to swim in, but do seem to like swimming as shoal in the flow.

I do have occasional dead fish, very rarely, but I certainly would relate it to too much flow, more likely over feeding on my part.

Did have the power head on a timer to match CO2 on time, but since replacing the timer not bothered setting it yet, so 5300l/hr in 180litre it is at the mo.


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## Edvet (21 Nov 2014)

Try to see some real life underwater movies, even quiet creeks flow MUCH harder than we usualy provide, i wouldn't worrie about flow being to much.I used high flow in the large tank ( two big koralia's 5000 and 100000 lit/hr) and it never bothered the fish.


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## Jose (21 Nov 2014)

Sacha said:


> So, is high flow bad for fish health? Does anyone even care? Whatever problems I've had on this forum, I've always been told to "improve my injection/ distribution regime". Well, I've definitely done that now, but I'm concerned about my livestock.



I do think this is a posibility.

I personally dont agree with the more flow/Co2 attitude to solve all problems although I understand that it is the main problem with beginners (not saying you are one). Also flow doesnt have to be huge but it has to be quality flow. Also too many people use huge amounts of light.


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## Jose (21 Nov 2014)

That being said you are probably better off looking for the cause of your fishs death somewhere else. Starvation could be but thats not the flow, thats you, not feeding enough.

I think a very good idea is to turn off most water movement when you are feeding.


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## KarthikC (21 Nov 2014)

Most barbs enjoy medium to high flow. They do good in well oxygenated waters. Bullying by other barbs might be the reason for your fish's death. I've collected many barbs from their habitat and the flow is high in most places  How many of those barbs do you have in your tank?

Cheers,

Karthik


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## Sacha (21 Nov 2014)

I only have 3 left. I used to have 6, but over the last few months their numbers have declined. I think it's just old age.


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## Jose (21 Nov 2014)

They were quite sensitive to CO2 in my tank. More so than tetras for sure.


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## Bhu (21 Nov 2014)

Let me relate a recent experience that may enlighten you. Just the other day one of my discus just hid all day long and clearly looked stressed, this is since adding a sera 1000 co2 reactor and a 1000-2000 lph external pump which was on about 1200lph. Now adding this pump doubled my flow rate to about 15x but the flow I could see clearly didn't bother my fish. I decided to reduce my co2 bps and the next day the said discus was back out and not looking stressed at all. One thing to note is that the discus still fed well but then hid after. Now the DC was just light green and not even hinting at yellow. But as soon as the co2 injection was reduced the discus after 3 days of hiding came out. I also noticed that the other fish seemed happier and were more relaxed with their breathing.

My conclusion was to add an airstone which is on 24/7 now to help with gas off of unused co2 especially when it shuts off and re-oxygenation of the water. I think the plants are letting me down a bit there!

If I were you Id leave the flow but focus on getting O2 into the tank, an airstone is essential I feel.

I did loose 2 leaves off of one crypt but the fish are all happy again. Now I have to try to increase the co2 slowly until I get a light green DC again. My lights are now only at 50% which were at 80% so now I need to get that back up as well. I think I will have to have the airstone quite strong to achieve that as the fish really do suffer this extra co2. When you consider that naturally in water its only about 3ppm and we are working with 20-30ppm plus at night there's huge competition for the O2 not just the fish and plants but microorganisms and critters too!

Make sure you have good surface agitation, but I had that so its not enough, try to introduce an airstone

It really is a challenge to get the equilibrium right. Even if you achieve this without fish on adding them it changes all the equations and you have to start again as more o2 is needed.

I don't think that its your flow being too high. As stated above in the wild millions of gallons pass by every few seconds. Our tank flows seem quite paltry in comparison. But what the wilds have is huge surface agitation and exposure to the air for constant gaseous exchange.


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## KarthikC (21 Nov 2014)

I agree. Surface agitation is a must with the barbs and other fish that need highly oxygenated water (like hill stream loaches for eg.) 


Sent from my iPhone using Tapatalk


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## Tim Harrison (21 Nov 2014)

It is tempting to blitz the tank with CO2, but IMO/E getting flow right is perhaps more important, but as stated not necessarily quantity but quality...I've reduced the CO2 input and my fish are much happier and plant growth/health hasn't suffered. So long as the scape gives the fish plenty of options with regards resting/hiding places where the circulation isn't quite so strong they will usually be fine.


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