Spray Bar and CO2 Diffuser placement confusion

[MMonis]

Hi,

I am going to rescape/restart a 54 litre aquarium and am planning on getting the necessary equipment before I start with the rescape.
Initially I was planning on getting steel lily pipes but felt that due to the jet type output, the flow may be too concentrated and I risk blowing off the carpet plants which I intend to establish.

After some research I thought of getting a Fluval Spray bar kit as it will fit well into my Fluval 106 cannister filter output. So no additional pipework/tubing changes or mods (to accomodate lily pipes).
I have also had poor circulation in the tank with the existing Fluval standard outlet, so hoping that the spray bar will solve the issue and provide both good circulation and surface agitation.

Since the length of my aquarium is 60 cms, I will need to connect both bars (15 cms each) so that the entire tank length is covered for circulation.
I plan to rescape the tank with a triangular layout, consisting of plants, driftwood and carpet plants (Marsilea Hirsuta). I will have an in-tank CO2 diffuser and will also use the standard inlet pipe of the Fluval 106.
I am confused in terms of placement of the spray bar, CO2 diffuser and the filter inlet.

The image shows the equipments and where I think to place them.

1) If the CO2 diffuser is placed towards the front left of the glass, will the CO2 bubbles reach the right side (back and front) of the tank where I intend to grow the carpet ?
2) If the CO2 diffuser is placed at the rear of the tank, next to the filter inlet, will this effectively distribute CO2 throughout the tank ?
3) What would be the best placement of the 3 components i.e. spray bar, filter inlet and CO2 diffuser considering my scape layout ?

Regards,
Mel.

 

[Libba]

I was facing this issue recently and felt like I wasn't getting good distribution regardless of placement. My guess is that your best bet would be to have your diffuser in a position such that your filter inlet is sucking in most of the CO2.

 

[MMonis]

I was facing this issue recently and felt like I wasn't getting good distribution regardless of placement. My guess is that your best bet would be to have your diffuser in a position such that your filter inlet is sucking in most of the CO2.

In this case if I place the diffuser at the rear of the tank near the filter inlet, wouldn't this be an issue with the carpeting/ foreground plants not receiving the adequate CO2 ?

 

[Zeus.]

Every tank is different but the aim the same, to have a even [CO2] (carbon dioxide concentration) though out the whole tank so that CO2 gets delivered to every plant you whish to grow, plus maintain that [CO2] from lights on for the main part of the photo period.

The Aim with the CO2 bubbles/mist is to delay them reaching the tank surface, having them rise in the main output jetted to front of tank pushed right down to the substrate then along the substrate. You will know when you have achieved this as your tank will look like '7up' - mine did 😉 ( well thought it looked like Gin and Tonic.)

Having the CO2 being sucked into the filter can work well as is basically using the filter as a CO2 reactor, if any CO2 bubbles/mist don't get sucked in and go straight to the surface of the tank they have limited time to dissolve. Also filters can only handle so much CO2 then then begin the 'burp' due to the build up of CO2 gas, I used this on a FX6 and I was limited to how much CO2 I could inject before the burping started, also CO2 can dissolve your seals in the filter also - but never heard of anyone having an issue. Many folk use low level CO2 injection and use the filters as reactors.

For higher level [CO2] and bubble free (except pearling) CO2 reactors are popular with many folk making DIY ones as the commercial products are not that impressive IMO/IME

I prefer the intake of the filter as low as possible so it removes the water near substrate which many not have a as high [CO2]. Having said that I do have on one of may tanks with the intake very high, however I have twin Maxspact Gyres forcing the CO2 enriched water right round the tank and my tank to output ratio is well above the x10 advised guideline at certain times of day, the guidelines are there to help and not rules. Your plants will tell you when you have it right.

So play the the diffuser placement and see what works well and suits you for viewing as well

 

[Driftless]

I am not a fan of spray bars, particularly in that size tank. See this article and look at the last graphic on the page. Surface agitation & gaseous exchange in CO2 injected tanks

 

[aquascape1987]

I have a similar set up with the spray bar on a 60cm wide tank, however my volume is approx double this. I inject co2 into a jbl diffuser on the flow line going back to the filter, and have no problems with burping when injecting co2 to get up to a stable 1.3ph drop and lime green on the drop checker. I find the Jbl ones produce finer bubbles than the Co2 Art ones, although you need to be careful to tighten them tight so that bubbles don’t escape around the membrane. Also no issues with damage to the filters.. Although I do use 2 x filters and inject into both, so this obviously reduces the amount that each filter has to handle. This gives results in the tank almost as good as a reactor, with no 7up effect. I also prefer a longer build up period for CO2 before lights on to get my drop, so instead of 1 to 2 hours before, mine comes on 4 hours before, which means the bubble count is less. It took me a while though to tune in stable CO2 this way, but for me was worth it, as I have stable high levels of CO2, no 7up effect, and also no burping of filters. My fish also seem to prefer a longer but slower injection rate as well.

Incidentally, my twinstar outlet is at the back on one side only, below the spraybar, and when it goes off, it sends bubbles to the front, down the glass and then they get all round the tank, even though the input is on one side only 🤷🏻‍♂️.

If it were me, I’d invest in an in line diffuser, but if you are sticking with the in tank diffuser, I’d first experiment with it next to the filter intake pipe, and see if you can get your desired level using the filter as a reactor, without it burping 😁

 

[Zeus.]

Incidentally, my twinstar outlet is at the back on one side only, below the spraybar, and when it goes off, it sends bubbles to the front, down the glass and then they get all round the tank

Twinstar is a great way to check the flow in tank IMO/IME

I’d invest in an in line diffuser

+1, even on the outlet they work well.

 

[JoshP12]

I'd put the CO2 diffuser into the inlet of your filter intake. And ensure your spraybar sprays right down the front and swoops to the back.

Put the inlet as close to substrate and diffuser as possible.

 

[ceg4048]

After some research I thought of getting a Fluval Spray bar kit as it will fit well into my Fluval 106 cannister filter output. So no additional pipework/tubing changes or mods (to accomodate lily pipes).
I have also had poor circulation in the tank with the existing Fluval standard outlet, so hoping that the spray bar will solve the issue and provide both good circulation and surface agitation.

Since the length of my aquarium is 60 cms, I will need to connect both bars (15 cms each) so that the entire tank length is covered for circulation.

Hello,
It is not always necessary to run the spraybar along the entire length of the tank. Be mindful when connecting additional bars that the pressure drop across the extra length will reduce the kinetic energy of the flow streams and may reduce the effectiveness of the spraybar assembly. A better strategy is to first use a single bar mounted at the center of the tank length and evaluate the effectiveness prior to adding a second bar. If you decide to use two bars then I suggest that you also do not fill the cannister to the brim with media. Remove all the stone type media and only use several coarse foam pads to improve flow rate.

Also review the sticky Water flow in the planted aquarium? at the top of this forum section.

Cheers,

 

[Mark Nicholls]

Here's a vid of my pkacement

 

[MMonis]

I am not a fan of spray bars, particularly in that size tank. See this article and look at the last graphic on the page. Surface agitation & gaseous exchange in CO2 injected tanks

If I think of good gaseous exchange and surface agitation, I know that my existing Fluval 106 outlet doesn't provide that. Hence, the move to either lily pipes or a spray bar.
If I look at steel lily pipes then there is only the jet outflow type (don't want to get into glass lily pipes as I will end up breaking them more and its also difficult to maintain them) and I feel the flow maybe too concentrated for my setup since I plan to grow a carpet.

 

[MMonis]

If it were me, I’d invest in an in line diffuser

After some further reading, I think this is what I am going to invest in. Feels like it has more pros than the in-tank diffusing method.

 

[MMonis]

Hello,
It is not always necessary to run the spraybar along the entire length of the tank. Be mindful when connecting additional bars that the pressure drop across the extra length will reduce the kinetic energy of the flow streams and may reduce the effectiveness of the spraybar assembly. A better strategy is to first use a single bar mounted at the center of the tank length and evaluate the effectiveness prior to adding a second bar. If you decide to use two bars then I suggest that you also do not fill the cannister to the brim with media. Remove all the stone type media and only use several coarse foam pads to improve flow rate.

Also review the sticky Water flow in the planted aquarium? at the top of this forum section.

Cheers,

Really great advice, and this has made me decide to do a DIY spray bar with different lengths and check what works out best.

 

[MMonis]

I have setup a DIY spraybar using PVC and drilled 6 holes with a 1/8 drill bit, spaced 3 inches apart.
Have set the CO2 diffuser close to the intake of the filter.
Here is a video showing the flow.
Does this seem right and any feedback on it to be improved ?

 

[Hufsa]

Looks vigorous. What is the clear hose kinked into the tank? Outlet? The kink of the hose will be cutting off a lot, you should get a U piece to go over the glass edge

 

[MMonis]

Looks vigorous. What is the clear hose kinked into the tank? Outlet? The kink of the hose will be cutting off a lot, you should get a U piece to go over the glass edge

The kink is on the intake to the filter. Yep, have to fix that during this week 🙂

 

[MMonis]

I haven't noticed burping in the canister filter when placing the diffuser under the filter intake as shown in the above video.
However, I am unable to figure out if the CO2 is being dispersed correctly by the spray bar or most of it is just escaping. How does one figure this out ?

 

[Paul Willi]

Try moving your drop checker to all areas of your tank over time and if it's always lime green during lights on then you getting good distribution. Can help to have more than one drop checker when setting up.

 

[ceg4048]

I haven't noticed burping in the canister filter when placing the diffuser under the filter intake as shown in the above video.
However, I am unable to figure out if the CO2 is being dispersed correctly by the spray bar or most of it is just escaping. How does one figure this out ?

Hi,
Whenever you make a change to your CO2 technique you should perform what we like to call a CO2 profile. This entails taking a series of pH measurements at the time that the gas goes ON and subsequently every hour or half hour until lights OFF, or at least gas OFF. Record the data and keep records so that you can compare the effectiveness of the change you made. Ideally, you'd like to see a 1 pH unit decrease from gas ON to Lights ON, and then you'd like to see that minimum value maintained all the way to gas OFF. It's difficult to get it perfect, but getting to within 10% is fine. Adjust the injection rate to achieve this. If you are pumping gas into the filter intake and if only a minimal amount of bubbles exit the spraybars then that is usually a good indication that your method is effective. If a lot of bubbles are spurting out through the spraybars then this is less effective and can be annoying but your pH profile will tell you how effective you are. There is no need to move DC around or to have multiple DCs.

Of course, that is only half the story. You also need to have good filter flow rate and the output needs to be distributed evenly across the length of the tank, so the spraybar holes should be pointed straight ahead.

Ultimately, it is the plants that will tell you whether your technique is successful or not. If you see new growth and if the plants do not show evidence of CO2 shortfall then you can be certain that you were successful.

Cheers,

 

[MMonis]

Thanks @ceg4048 for the detailed reply. Your inputs are always so helpful.

Whenever you make a change to your CO2 technique you should perform what we like to call a CO2 profile. This entails taking a series of pH measurements at the time that the gas goes ON and subsequently every hour or half hour until lights OFF, or at least gas OFF. Record the data and keep records so that you can compare the effectiveness of the change you made. Ideally, you'd like to see a 1 pH unit decrease from gas ON to Lights ON, and then you'd like to see that minimum value maintained all the way to gas OFF. It's difficult to get it perfect, but getting to within 10% is fine. Adjust the injection rate to achieve this. If you are pumping gas into the filter intake and if only a minimal amount of bubbles exit the spraybars then that is usually a good indication that your method is effective. If a lot of bubbles are spurting out through the spraybars then this is less effective and can be annoying but your pH profile will tell you how effective you are. There is no need to move DC around or to have multiple DCs.

Attempt 1:
I increased the bubble rate from 1 to 2 bps and following was the pH profile measured by API Drop Test Kit:
9:45 am : Before CO2 on: 7.0
11 am: 1 hr after CO2 on : 6.6
12 noon: 2 hrs after CO2 on: 6.4
1 pm: 3 hrs after CO2 on, lights on (sunrise: 30 min ramp up) : 6.4
1:30 pm : All lights on at 35% intensity : 6.4
The CO2 remained between 6.4 and 6.2 thereafter, but since I could not achive the 1pH drop by lights on, I abandoned this approach

Attempt 2 (next day):
I increased the bubble rate from 2 to 2.5 bps and following was the pH profile measured by API Drop Test Kit:
9:45 am : Before CO2 on: 7.0
11 am: 1 hr after CO2 on : 6.4
12 noon: 2 hrs after CO2 on: 6.2
1 pm: 3 hrs after CO2 on, lights on (sunrise: 30 min ramp up) : 6.1/6.0
1:30 pm : All lights on at 35% intensity : 6.1/6.0
This remained stable till the CO2 off at 4:30pm (lights start dimming from 5:30pm and - sunset and switch off at 6pm)
However, the drop checker seems yellow, so am not sure if I am actually overdosing CO2. At the moment I only have Amano shrimps in the tank but was wondering if this would be an issue when I add fish to the tank. I do not have an air stone or skimmer, but relying completely on the surface agitation by the spray bar.


I am kind off doubting the tests done using the API Drop Test Kit as the lowest it measures is 6.0 and am not sure if my pH drops below that or not. Also, the chart color between yellow (6.0) and faint-green (6.4) is difficult to judge.

Of course, that is only half the story. You also need to have good filter flow rate and the output needs to be distributed evenly across the length of the tank, so the spraybar holes should be pointed straight ahead.

I think I have a decent flow as I can see that the leaves are gently swaying. The spray bar runs accross the tank and has 6 holes roughly 1/8" diameter. Is there a way to test if the flow is a complete circular motion by adding something to the tank?