# BBA and High Flow



## Greenview (1 Feb 2012)

I have been containing BBA for a few months now; there has not been lots of it, but because it is on leaves I am concerned. I have spraybars from a pair of Eheim 2217s across the back of a 180 litre tank, and a Koralia 1600 between them pushing the CO2 forward from a diffuser just below it. There is an excellent stream of bubbles in the Koralia's high flow but the BBA seems to relish growing right there. Two days ago I removed a large stem plant (with 50% water change) and this opened up the back of the tank; I also cleaned one of the filters, and the BBA has exploded on the hardscape in the usual places. It looks like it loves the increased flow. Is this common? I have read a couple of posts suggesting it so I will go with my hunch and swap the koralia 1600 for a 900, and will see how things go. I might even run the diffuser through a filter intake and dispense with the koralia entirely. I am increasing the water changes (in case lower plant mass is at fault). But I really don't like the idea of reducing flow and wondered what those with more experience thought.

Specs: lights 2WPG for 6 hours; EI dose ferts; easy carbo spot dosed 2x dose daily for last 3 months (reducing dose increases algae). Lime green drop checker but there is not much room for increasing before fish gasp.


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## hotweldfire (1 Feb 2012)

My experience is limited but I think pertinent. I have an Eheim 2071 running at half speed (so probably about 600 lph) with outlet at back right pointing across the back of the tank. Then a Koralia 1600 at the front left top corner pointing back across the tank to the right but angled down to hit the substrate. Tank is 125l, co2 via inline diffusor. Aim of course is to get circulation right round the tank but I think what actually happens is flow from Koralia hits front bottom right corner then bounces back across front of tank.

Really good healthy growth but loads of BBA on the hardscape. One plant struggling at the back (H. pinnatifida) and it was under the eheim so I assumed it wasn't getting enough co2. So I added a koralia nano to bottom right corner underneath the filter outlet so it was blasting the pinnatifida.

Plant is now recovering and looking promising. More interestingly the BBA disappeared completely in one week. No sign of it now. Note I did not change anything else.

The weird thing is that the koralia 1600 was pointing down to the carpet and to the hardscape that is just behind it. Thus both carpet (HC and elatine hydropiper) and hardscape are getting blasted with co2 with the carpet flourishing and my dragon stone covered in BBA.

Adding the second koralia appears to have improved circulation such that the co2 that was bouncing around the area with BBA is now getting pulled to the back of the tank. At the same time the BBA is gone  :? 

Maybe before swapping out the koralias add the nano as well? Maybe put it on the front glass low down pointing to the back of the tank? Obviously not a long term solution as you don't want something stuck on the front glass but maybe do that for a week and see what happens?


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## Dolly Sprint 16v (1 Feb 2012)

Hi Greenview

Have a read at the attached:

http://ukaps.org/forum/viewtopic.php?f=19&t=19834

Regards
paul.


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## Greenview (1 Feb 2012)

Thanks both of you. That thread and Hotweldfire's comments seem to confirm my suspicions. That is an interesting thought about using another circulation pump in addition, and it might be worth experimenting with directing flow elsewhere. I will think about that. What I did not tell you is that the algae grows at the front of a mock river going back through the tank and on the leaves and carpet lining the river; the removed stem was at the back to the side of the river and I think I might have further increased flow down it by removing the stem. Adding another pump down the river might not do anything as it is unobstructed flow down the river.

I have two other considerations sparked by the content of the other thread, and wonder what folk think. While the BBA undoubtedly happens where there is lots of flow from the pump, is the flow the cause or something else? 
1. Is the BBA happening at a place of turbulant flow rather than high flow? The pump and spraybar point in the same direction, but their cones of flow will interfere to an extent, is there an interface between CO2 rich koralia flow and CO2 less-rich spraybar flow which is causing parts of the tank to have fluctuating levels of CO2 as these flows interfere with each other (e.g. by waving plants causing oscillations in flow)? 
2. Is the BBA happening where there are loads of CO2 bubbles blown by the pump? I can imagine these giving high CO2 if they land on something and less when they do not. 

The solution to both options would seem to be getting rid of the Koralia and trying to run through a filter, but I still have fears (albeit irrational ones) about filter integrity if I do this. The solution to a flow problem would be replacing the pump with a less powerful one. I am be overthinking this (but you got to have something to learn from algae, right?), and I will experiment and report back. I will need to get a new pump first (I need one for another tank anyway!).


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## sanj (3 Feb 2012)

Another option would be to keep an SAE or few, although if this is your biotope setup you may not want to.


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## Greenview (3 Feb 2012)

It is not the biotope, so an SAE or two might be an idea. I saw your thead on them and it was quite enlightening. I would sooner get the CO2 delivery sorted out and keep BBA at bay that way though.


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