# Diatoms - insufficient filtration?



## gargamelcz (18 Aug 2011)

Hi, I have problem with brown algae, I guess that it's a diatom on the photo.





My tank:
300l tank 120 x 50 x 45, light 0,5 W/l - 10 hours per day, CO2 - Pressurised through day.
I used to dose by EI method, but I wasn't able to ensure enough CO2, so I transfer to PPS Pro. Algae situation is now kinda cool, because i get rid of BBA and green thread algae, but there is still this crap.
I think, that problem could be in my filtration. In tank is EHEIM 2215 - 600 litres per hour and real flow is around 300 l/h - filtraton media capacity 4 litres. Better circulation ensure two powerheads. More on the photo:




I read about NH4, which could cause diatoms in new setup tanks, but my tank is matured and diatoms is still here. So i have suspicion, that it's all about filtration media. I wondered, that I should add big sponge onto powerheads. What you think about that, is it all about insufficient filtration? Thanks for advice.


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## GillesF (18 Aug 2011)

Hi Gargamel

how much L/H does each powerhead have? You should aim for 10x the tank volume, in your case that would be 3000L/H.
You say you cannot provide enough CO², why do you keep so much light then? Less light = less CO² & fertilizer demand. I'd cope with the CO² first and then the filtration.


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## gargamelcz (18 Aug 2011)

Hi, aggregate power of filtration and powerheads is 1500 l/h.
I know, that I should aim for 10x the tank volume, but I thought, that it's neccesary only with Estimative index, so I transfer to PPS Pro, because I can not accept so high flow and high demand of CO2. In PPS Pro recommend much more lower amount of CO2 and water flow. http://sites.google.com/site/aquaticplantfertilizer/home/co2-injection, that's, why I stopped using EI.
I dont think, that 0,5 W/l is "so much light", I even cut light off to 0,3 W/l now, but situation with diatoms is not better.
I'd like to run my tank without algae with this flow and lesser amount CO2 around 20 ppm. Is that possible?


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## GillesF (18 Aug 2011)

10 hours of 150 watts seem a lot to me (T5) but I'm no expert on lighting, maybe someone else can help you with that. The main importance is to get a good lighting & CO2. Too much light and you won't be able to provide sufficient CO2 --> algae.

The reason why good flow is needed is to have a good and even distribution of CO2 and fertilizers. This will improve plant growth --> less algae. I've never used PPS Pro so I can't help you with that either, but some things on that webpage seem a little outdated though.

*edit* Have you recently disturbed the substrate by the way?


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## ceg4048 (18 Aug 2011)

Hi,
   I think you might be a bit confused about a couple of things from what I can see in your reasoning. For example, I find the following statement to be completely unreasonable:


			
				gargamelcz said:
			
		

> I used to dose by EI method, but I wasn't able to ensure enough CO2, so I transfer to PPS Pro.


EI is not really dependent on the ability to ensure any specific level of CO2. Furthermore, the required level of CO2 is a function of primarily the lighting level, not the nutrient level. Although it is certainly true that CO2 uptake drives nutrient demand and vice-versa, everything starts from the light intensity, so if one has a problem CO2 delivery, the fix is in reducing the lighting level, not necessarily reducing the nutrient level. Even so, with lower CO2 levels EI is flexible enough that all you need to do is to lower the dosing amounts by 20%, by 30% or by whatever percentage. EI is even applicable to non-CO2 tanks and the dosing levels are very small but is still very effective.



			
				gargamelcz said:
			
		

> ...I read about NH4, which could cause diatoms in new setup tanks, but my tank is matured and diatoms is still here. So i have suspicion, that it's all about filtration media..


 Diatoms are all about light and stability. You might want to try a blackout.



			
				gargamelcz said:
			
		

> power of filtration and powerheads is 1500 l/h.
> I know, that I should aim for 10x the tank volume, but I thought, that it's neccesary only with Estimative index, so I transfer to PPS Pro, because I can not accept so high flow and high demand of CO2. In PPS Pro recommend much more lower amount of CO2 and water flow. http://sites.google.com/site/aquaticpla ... -injection, that's, why I stopped using EI.


Again, this is a complete misinterpretation of reality. As a matter of fact, you need even more flow and better distribution if your CO2 is inadequate, not less flow. If your flow is poor you need more nutrients, not less. As GilesF quite rightly points out, the purpose of flow and distribution is to deliver CO2 and nutrients to the surface of the leaf. It fundamentally has nothing to do with whether you use EI or PPS, although, as mentioned, there are some ramifications.

I would advise to use a stronger filter with extended spraybars, or stronger pumps. 300 liters is a lot of water, and your problems will only get worse, not better. You're headed for a future train wreck using this system of logic, because the assumptions you've made are basically illusions.

Cheers,


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## gargamelcz (19 Aug 2011)

Hi,
Firstly, I'd like to appreciate your help and thank you for your advice. I'm from Czech republic and situation around planted tanks is not good here. For example, people are convinced, that water flow is undesirable and could cause algae. My tank with flow around 5x tank volume per hour is for them totally insane. I used to run my tank without water flow and I was kinda succesfull:




Then, I switched to EI with flow around 5x tank volume per hour, but there was a little algae:




Current situation with PPS Pro method and problems with diatoms (GillesF: yes, I recently disturbed substrate, but diatoms is there for a long time):




On the other hand, I believe, that it's possible to run planted tank with lower flow than 10x per hour(but I definitely don't claim, that flow can cause algae - it's stupid). As an example is this tank completly without flow - big filtration media and flow 0,5 x the tank volume per hour: http://www.akvarko.cz/akvarium.php?nadrz=2488


> EI is not really dependent on the ability to ensure any specific level of CO2. Furthermore, the required level of CO2 is a function of primarily the lighting level, not the nutrient level. Although it is certainly true that CO2 uptake drives nutrient demand and vice-versa, everything starts from the light intensity, so if one has a problem CO2 delivery, the fix is in reducing the lighting level, not necessarily reducing the nutrient level. Even so, with lower CO2 levels EI is flexible enough that all you need to do is to lower the dosing amounts by 20%, by 30% or by whatever percentage. EI is even applicable to non-CO2 tanks and the dosing levels are very small but is still very effective.


Probably I am again wrong, but I thought, that higher CO2 levels with using EI are necessary, because there are a lot of nutrients - as well as light, which could cause algae. But with enough CO2 it's ok... With PPS, I don't have a large amount of nutrient in the water, so level of CO2 can be lower - as well as accessibility - lower flow. Am I wrong?
Secondary, currently I use CO2 mist, do you think, that CO2 reactor would be better choice in my situation? Better accessibility?
I'm grateful for every piece of advice, because I'm quite confused.


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## GillesF (19 Aug 2011)

Hi Gargamel

Firstly, fertilizers, CO2, lighting, ... do NOT cause algae. Instability and poor plant growth is the cause of algae problems (e.g. too much light compared to your CO2 injection). The EI is just an easy way of adding fertilizers to your plants without doing weekly tests. 

If you want to use less CO2 and fertilizers than you could use less light. This decreases the demand for nutritients because plants consume less "energy" (slower growth). You should always have good flow, there's no point in decreasing it. Good flow is important for the distribution of the nutritients.

I use an inline atomizer and I'm happy with it. A reactor is good too I guess but keep in mind that it will reduce flow ...

Hope this helps,
Gilles


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## ceg4048 (19 Aug 2011)

Hi,
    Yes it's entirely possible to run high tech tanks with lower flow. As in all things we have certain general rules which are meant to keep people out of trouble, especially if they don't understand the principle - but this does not mean it is impossible to break the rule and still be successful.

Sometimes it's also a matter of luck. For example, if the light energy is not strong then the demand for nutrients and CO2 are also less. People get lucky all the time. I've even seen where some people claim that plants don't need nutrients, and they show examples of  beautiful tanks in which they claim that no nutrients are added. But a closer investigation reveals that their water supply is high in nutrients so in fact every time they do a water change they are actually replenishing the nutrients in the tank without realizing it. Additionally, it's possible to get lucky with the aquascape. Open, Savannah type scapes have less blockage and so the flow is better across the tank. Even the types of plants will have an effect on luck. Some plants require much less CO2 and nutrients than other plants do and so will do well even under a lower dosing regime and lower CO2. Plants also have the ability to adapt to their environment as long as the weaknesses are not too extreme, so it's possible to have difficulty in the beginning and after a while, if the environment is not too severe the plants make the chemical adaptations to survive and grow under those conditions if the conditions are stable.

So the possibilities are endless, however, once you begin to change the environment beyond their ability to adapt you get into trouble.

One of the main problems with PPS dosing is their reliance in test kits, so this adds to the illusion that somehow, you are "controlling" the nutrient levels, when in fact nothing of the sort is occurring. Nitrate and Phosphate test kits are useless in giving you consistently accurate results so people fall into the trap of thinking they know what's happening in the water when actually they are depending on luck without realizing it. Then they see the results and they draw false conclusions about cause and effect.



			
				gargamelcz said:
			
		

> but I thought, that higher CO2 levels with using EI are necessary, because there are a lot of nutrients - as well as light, which could cause algae.


Here is a fundamental error. Nutrients can never cause algae. Algae do not care about the nutrient level in a tank. What algae care about is the overall health of the system. If the system is weak and if plants are unhealthy the algae can sens the suffering and they attack. If the system is strong and healthy then algal spores will not bloom.

There is a fundamental relationship between light, CO2 and nutrients. High light causes the metabolism of plants to accelerate. When this acceleration occurs the plant must gather CO2 more quickly. When CO2 is obtained more quickly the reactions with nutrient components occur more quickly - which means the plant needs to absorb nutrients more quickly. If either the nutrient availability or the CO2 availability is interrupted the plant suffers - and algae will attack.

It's very important to realize that an interruption in nutrient availability can occur whether or not the tank is dosed with high level of nutrients. The same for CO2. There are environmental factors that can occur in the tank which block the plants ability to feed. Therefore it's very possible for someone to be dosing high levels of nutrients and yet the algal blooms occur. People who don't know any better then conclude that the algae was due to high nutrients, but again this is false. The real problem is that although nutrient levels are high, something is blocking them from entering the plant at a fast enough rate to satisfy the growth rate demand from the lighting. This happens often in tanks with low flow. The purpose of flow is to act as a carrier of nutrients and CO2 to the surface of the plants. The surface of the plant leaf is coverd with a film that contains many organisms including algal spores. The nutrients and CO2 have a difficult time crossing this film and in entering the plant membrane. When the flow across the leaf is sufficient the waste products can be carried away and replacement CO2 and nutrients can enter more easily.

Flow delivers nutrients and CO2 to the leaf. Again, this does not mean that low flow automatically causes problems. That depends on the other variables occurring in that environment. But it's easy enough to follow a set of guidelines which minimizes the risk of poor nutrient and CO2 uptake. The higher the lighting the greater the risk of starvation and the more important it is to follow the guidelines in order to minimize that risk. Algal blooms occur when there is a deficiency of nutrients - never when the plant has access to more nutrients. This is a really important principle to understand because it is the basis of which we troubleshoot problems in the tank.

I'm pretty sure, as you mention, that in Czech Republic people suffer algal blooms all the time, just as people do in UK, Germany or USA. Algae have no country and they don't care about anything else except whether or not the plants in their tank are healthy. For every example of a successful tank you show with low flow and low nutrient dosing, I'm confident that you will find hundreds of tanks, following  the same technique which are a disaster. And that's because people in every country believe the wrong things - that nutrients cause algae and that high flow is bad. But this is so easy to disprove and we do it here all the time.

You can use EI dosing with high CO2, which gives the greatest benefit, or you can use it with low CO2 - algae don't care. Whichever dosing method you use you have to ensure that the plants are healthy, otherwise nothing matters. When you can understand some of the science of plant growth, it will be easy to understand when you can deviate from the rules and why a tank can be successful even when breaking the rules.



			
				gargamelcz said:
			
		

> ...currently I use CO2 mist, do you think, that CO2 reactor would be better choice in my situation? Better accessibility?


Well, theoretically, a mist should work better than an ordinary reactor so I wouldn't change that at all, but I would suggest to use the biggest and strongest filter you can afford, and to extend the spraybar along the entire length of the back wall attached to that strong filter.

If you don't want to do a proper blackout, then just do a "soft" blackout by simply leaving the light off and allowing only ambient light into the tank for a week or so.

Cheers,


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## GillesF (19 Aug 2011)

Ceg, thanks for the info, I'm definitely using some of this for my blog. Just a quick question: is it always better to have spraybars at the back instead of left or right? I think that my H. Callitrichoides didn't want to grow due to bad flow and not too low light.


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## gargamelcz (19 Aug 2011)

Great article, thanks a lot. I'll translate it and publish on Czech forum.
I'll definitely improve my circulation and I'll instal spraybar. But I have to cut my light till it will be installed - it can takes weeks. I have 3 36W tubes - T8 above my tank - it's 0,36W/l. Should I switch off another tube - it give me only 0,24 W/l T8. Is it enough?

But I am still curious how come, that this tank: http://www.akvarko.cz/akvarium.php?nadrz=2488 is so succesful, even though there is no flow. You said, that's all about luck mostly, but can you explain reasons, why this particular tank is succesfull? I'll translate something about that tank:
tank volume 720 litres
light 0,4 W/l T8 tubes
volume of filter - 60 litres and flow rate only 400 litres per hour!
no sprabarr, nor powerheads
temperature 28° to 30°C.
Fertilization: PPS
Small amount of CO2 - max 2 bubles/sec.
Water changes once a week 100 litres.


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## ceg4048 (20 Aug 2011)

GillesF said:
			
		

> Ceg, thanks for the info, I'm definitely using some of this for my blog. Just a quick question: is it always better to have spraybars at the back instead of left or right? I think that my H. Callitrichoides didn't want to grow due to bad flow and not too low light.


Hi Gilles,
  You're very welcome. Generally, I've found that it's better to mount the spraybars along the back wall because the short distance to the front makes better use of the flow energy. I imagine that if the flow is strong enough then mounting it on the side wall would be OK. As with all things there are mitigating circumstances. In very small tanks for example it doesn't really matter which wall the spraybars are mounted on, however, I mostly deal with large tanks and so it makes an enormous difference because the distances are large and the resistance to flow greater. Have a look at the thread http://ukaps.org/forum/viewtopic.php?f=37&t=3827 for examples of how I prefer to mount my spraybars.



			
				gargamelcz said:
			
		

> But I am still curious how come, that this tank: http://www.akvarko.cz/akvarium.php?nadrz=2488 is so succesful, even though there is no flow. You said, that's all about luck mostly, but can you explain reasons, why this particular tank is succesfull? I'll translate something about that tank:
> tank volume 720 litres
> light 0,4 W/l T8 tubes
> volume of filter - 60 litres and flow rate only 400 litres per hour!
> ...


It's very difficult to assess the performance of any tank from a distance, especially if we do not know the hobbyist and if we are not there to determine exactly what was done. All we have are a few statistics and we must analyze based on the truths that we know. Also, remember that what you see in the photo is a finished product. We do not know (or at least we can't tell if we don't speak Czech!) what has occurred up to the point where the photos were taken. How long did it take to achieve the finished product? What problems did the hobbyist have along the way? How were the problems (if any) solved?

let me tell you another secret illusion of the plant hobby. The water column is only one method to fertilize plants. The other method is the sediment. Plants can and do use nutrients from both locations. I often see where people talk about lean dosing but they are using an enriched sediment such as Aquasoil Amazonia. Few people realize that Amazonia produces a sediment nutrient concentration of up to 100X EI water column values. So the sediment can have almost a 2000ppm Nitrate levels. Even if a sediment is not enriched, with time, food, plant matter, and residual quantities of dosing enter the sediment and accumulate so that the sediment becomes enriched. Nutrients can then leech out of the sediment and even fertilize plants that are not rooted.

So just imagine, even if you don't dose very often, but if you feed the fish, urine, feces and uneaten food can still produce NPK. If the tank is sufficiently aged and if there is enough organic matter in the sediment the bacterial action in the sediment produces CO2 which results from respiration of the bacteria in the sediment. this CO2 can augment the CO2 being injected.

We can see that the lighting is not outrageous. It's just under 300 watts - but this is T8, not T5, and we do not know the PAR values but we do know they won't be as high as what's in your tank. This is therefore a low stress tank. This is completely consistent with what we know to be true about plant growth.

As I mentioned before, we do not know what kind of water is being used. I do know that Czech river systems are typically over low solubility sediments such as granite, and that the waters are generally soft and with low mineral content. That's why Czech Pilsners and Lagers are among the most excellent in the world, but it's not clear if that is true in this particular case.

It's not my intent to belittle or insult the owner of those tanks by implying that it was all just due to luck. That would be totally unfair. They are absolutely beautiful and very well executed tanks. The owners are certainly excellent hobbyist. But what I am saying is that sometimes people do the right things for the wrong reasons, and that is what I mean by luck. For example, I see a lot where people do frequent water changes thinking that they are "getting rid of Nitrates". As it often turns out, the water that they use is unwittingly high in Nitrates and the tap water is high in CO2, so what they are actually doing is to provide clean water, which plants love, add Nitrates which the plants have consumed, and replenished CO2. The plants do well but, they conclude that it's because they followed a strict policy of "keeping Nitrates low." Nitrate test kits are terribly inaccurate and it can easily be that the test kit reads low when the Nitrate value is actually quite high. As a result, it becomes very difficult to convince these people about the truth because they put their trust in events that may be coincidence, and if the coincidence happens to be in their favor then they are lucky!

When you set up a tank, if you don't put too much pressure on them to grow they can adapt to the condition. For example, if the lighting intensity falls slowly, plants have the ability to increase the "population density" of the chlorophyll in the leaf. That means more pigment cells per unit volume. More density makes better use of less light. If the light falls off slowly the pigment density change has sufficient time to be performed. We can then slowly increase the light intensity and we will see that the density of Chlorophyll is slowly reduced as a result. But if these changes occur too rapidly, the plant cannot respond with enough agility to compensate and it may become damaged.

The same happens for CO2. If we slowly reduce the CO2 level in the tank, we will naturally see a decrease in growth rate and mass but the plant will become more efficient at gathering CO2. Plants in high CO2 tanks are extremely inefficient because there is so much CO2 available that they use their energies to accomplish other things such as producing flowers. The problem is that if there is a sudden downward change in CO2 they are unable to make the adjustments quickly and often starve because they have not produced a sufficient quantity of CO2 uptake proteins to be able to deal with the sudden loss of CO2. This means that the same plant can either fail or prosper depending on the rate of change of environmental conditions. it is not necessarily because of poor conditions that they fail. If they have had the opportunity to adapt to the low flow, low CO2, low light conditions, then of course they can do well. 

That's why it's not easy to look at a picture and to immediately assess why a tank is in good shape. The fact is that we know the truth however. We know that nutrients cannot cause algae because we add very high nutrient levels and we get high growth and excellent health. We know that adding high flow helps the plant grow. We can see the results, and we know that these are the typical cases and if you follow these general rules you have a better chance of success than relying on the reverse.

Have a read of the threads for more information:
Why dont nutrients cause algae?
Do excess nutrients = algae? Is it possible to "know"?

Cheers,


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## GillesF (20 Aug 2011)

Ceg,

do you happen to have some scientific articles that prove that fertilizers do not cause algae? Or simply experience?
I'm just looking for sources to back-up my blog article


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## ceg4048 (21 Aug 2011)

Hi Gilles,
            Here's one paper that Barr references =>Relations between trophic state indicators and plant biomass in Florida lakes

The "Trophic State" of a body of water refers to the concentration level of nutrients in the water. The following general categories are seen in the journal:
Oligotrophic = Very Low Nutrient Levels
Eutrophic = Medium Nutrient Levels
Hypereutrophic = High Nutrient Levels

A couple of other definitions of words found in the journal:
Polymictic - bodies of water are shallow and the temperatures of the water is close to being uniform from top to bottom as a result.
Secchi depth - is a measure of the clarity of the water. A Secchi disk has an alternating pattern of black and white. The disk is submerged in the water until the pattern disappears.
Planktonic - refers to the microscopic plant life suspended in the water.
Macrophyte - refers to the plants we grow.
Periphyton - refers to the microscopic plant and animal life in the thin film covering the surface of submerged objects, including the surface of macrophytes.

Basically, of the over 300 lakes studied, there was not much correlation in terms of algal mass with the trophic state of the lake. Some lakes were algae dominated and others were macrophyte dominated. When either dominated the lake, it was found that the nutrient levels could be high, medium or low, which means that there is no direct correlation between the nutrient level and algae domination. That means there are other, less well understood factors that determine whether algal blooms are present than just what the nutrient levels are.

We can also see the same lack of correlation in our tanks. EI tanks can be either eutrophic or hypereutrophic depending on the hobbyists dosing. Algal blooms may or may not be present in the tank.

If nutrients cause algae then it should always cause algae when present. There should be no exceptions, yet there are plenty of EI fed tanks that are algae free, so while we may not be able to conclude what the causes are we can show what are NOT the causes.

Just have a look at the photos in the EI tutorial viewtopic.php?f=34&t=1211. The health of these plants are honestly come by, and in fact the tank was dosed triple EI just to prove that nutrients are not correlated to algal blooms. No blooms were present in this tank until I left the tank for several days without feeding it. Resumption of the dosing regimen eradicated the bloom.

Cheers,


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## GillesF (21 Aug 2011)

Wonderful, this will be very useful to convince more experienced aquarists, thanks!


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## gargamelcz (21 Aug 2011)

Again thanks for explanation. I see what you mean and I can see myself in this description, because I ran my tank without these rules and my success weren't stable. One time, coloration and grow of plants was incredible and then came time of algae bloom. 
I guess, that water circulation is fundamental for me now.I read this thread http://ukaps.org/forum/viewtopic.php?f=37&t=3827 and your post. I found out, that my circulation was horrible. I intend to place a large spraybar on the back like this:




Right side: This is detail of cylinder bottle. This should be something like CO2 reactor. Whirpool should ensure 100% disolve of CO2.




I have some questions about that.
1) My overall power of powerheads and filter will be 2000 litres per hour. You sugest 3000 l/h, but this is real power because powerheads don't have to push water through filter media. Is it enough?
2) Is it possible to dissolve CO2 in this way? Or it's better to use CO2 mist, because I want to save some gas.
3) You wrote, that holes from your spraybar point straight to the front glass, because of the better circulation. But if I put holes down, flow is much bigger and plants sway moch more. Why do you prefer first case?
4) Will it work?


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## ceg4048 (21 Aug 2011)

Hi gargamelcz,
                      I have not used that method of ganging pump outputs into a chamber before but I do know that this technique is valid as long as the chamber is big enough. I assume that with the turbulence in the chamber you should get good mixing of CO2 unless the placement of the injection tube is too close to the spraybar inlet, in which case the bubbles might escape prematurely into the spraybar. You'll have to experiment with this.

There are a few reasons why I prefer to point the jet streams perfectly horizontal.
Remember that we are trying to create a smooth, non-turbulent rotation of water in a circular fashion. The front glass of the tank guides the water downwards and when it reaches the substrate the floor of the tank then deflects the flow to the rear of the tank. The rear wall then deflects the flow upwards. When we push the large mass of water in this pattern it delivers CO2 to the carpet plants and it also removes waste products from the plants and carries them away. If you point the flow downwards then the flow is chaotic as it reaches the substrate. This can actually starve the background plants because the flow can spill out towards the front as well as towards the rear. I'm not saying that this will automatically happen in your case. It's possible that the way you have done it will work. There are so many variables. But I always try to stay with the plan that we know works and only make adjustments if it fails.

Another reason I like to have the horizontal flow at the top is because this allows me to agitate the surface to break up any surface film that develops.

It is not in the best interest of the plants to punish them with hard flow. This can damage them as well. What we are trying to accomplish is to eliminate stagnant water in the vicinity of the leaves, so if we see them gently "swaying with the breeze" then we know we have achieved good flow.

I agree with your assessment of the powerheads as long as the connections are not so constrictive that their flow is choked. I think it's a good idea to try this and make adjustments based on the performance.

Hope this clarifies.

Cheers,


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## gargamelcz (21 Aug 2011)

OK, I have last few questions:
I made some modifications:




1) These hoses and spraybar will protrude and won't be smoothly with side of chamber. It'd be very complicated to place it smoothly with side of chamber. Is it problem? (possibility of bad turbulence and bad mixing of CO2?)
2) Let's say, that filter output give power of 600 l/h and two powerheads another 800 l/h. But I'm not sure, if the overall power in spraybar is 1400 l/h.
3) There will be two directions of flow in the spraybar - from left powerhead and 3 other sources from right. Will be flow from holes of spraybar even?
4) Is there posibility, that disolved CO2 will jet only from holes on the right? Left side of the tank would be then without CO2 and plants would starve.
I am aware, that these problems are more technical, but if anyone more experienced knows answers to these questions, please answer.
Thanks.


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## ceg4048 (22 Aug 2011)

Hi mate,
           This would be a very difficult mathematical equation to solve because it's tough to predict the static and dynamic pressures across the every nook and cranny of the chamber. The larger the chamber the easier it is to predict. If the chamber is too small, then all the factors have a significant impact, i.e. the flow from each pump fight against each other and reduce the total output, possibly even back-pressuring the weaker pump, the protrusions cause interference of flow, the bubbles are confined to a corner, and instead of mixing, the blob of gas grows until a segment of the blob is thrown into the spraybar which then spits bubbles out of it's holes.

If possible, I'd try yo keep the spud inputs to the chamber on the same side, separated at even spaces between them as neatly arranged vertically as possible and all pointing in the same direction instead of at different angles as you have shown. I might even think about placing the spraybar at 180 degrees from the inlet spuds (the weaker of the pumps directly across from the spraybar). The chamber should be approximately the size of a coca-cola can. The CO2 would come directly below the lower pump inlet.

Theoretically, the gas coming from the bottom would rise and would immediately have to run the gauntlet of the three pumps as it rises. This gives each bubble a chance to dissolve on it's way up to the top of the chamber. The large chamber size ensures the least amount of interference from protruding spuds and unequal inlet pressures. The spraybar spud at the top helps to reduce the gas buildup at the top by providing an escape route for wayward bubbles which can then enter the spraybar and will have a chance to dissolve further (you might still get some buildup in either the chamber or the spraybar at high injection rates).

Again, this is all theoretical and may not be the best solution, ultimately, but it's always a good place to start.

Hope this helps...

Cheers,


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## gargamelcz (24 Aug 2011)

Hi, I adjusted chamber according to your advice. Here's the layout. The chamber will be in size of two coca-cola cans.




I hope, real flow won't be significantly lower than summary power of all powerheads.
PS: I rearranged spraybars in my tank 4 days ago. The power is the same now, but only place spraybars to the back wall caused healthier grow of plants and decrease of algae. I believe new large spraybar will bring excellent results.


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## ceg4048 (24 Aug 2011)

Hi mate,
           Yes, I'm sure you'll get great results. You can verify the flow rate by disconnecting the spraybar  and by holding a container of know volume below the outlet. Then, run all pumps andmeasure the time it takesto fill the container. You can then calculate the real flow rate into the spaybar.

Cheers,


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## GillesF (24 Aug 2011)

You might add an in-tank atomizer (e.g. http://www.ebay.com/itm/Best-CO2-diffus ... 3a695583e3) to create smaller bubbles


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## ceg4048 (24 Aug 2011)

Yes, that's also a great idea, seeing as how you will use a fairly large chamber, this will help diffusion even more!

Cheers,


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## gargamelcz (25 Aug 2011)

Thanks. I'll experiment with that. On the other hand, I don't wanna have CO2 mist, because 100% dissolved gas looks more natural and CO2 mist would escape from water too fast because of the place of spraybar.


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