Tropical Fish Forum

Tropical Fish Keeping Help and Advice => Fish Tank Plant Advice => Topic started by: Matt on April 12, 2018, 05:00:33 AM

Title: Optimising plant fertiliser dosing
Post by: Matt on April 12, 2018, 05:00:33 AM
This was a secondary factor that put me off the use of liquid carbon - that whole notion of having to dose a measured amount every day...

Are you not dosing your plant ferts daily? Most bottles say to dose weekly but this creates the same issue... fluctuating nutrient levels in the tank. By splitting the dosing up across the week you can create a much more stable environment for your plants and fish. I just do it as part of my morning routine.
Title: Re: Optimising plant fertiliser dosing
Post by: Sue on April 12, 2018, 09:11:07 AM
The other side of that argument is that it is not good for fish to dose every day. I know that the amount added to the tank in one go is larger when dosing once a week, but the argument is that it better for fish to add things on as few days as possible.

We are now getting into aquatic gardens vs fish tanks with plants  ;D
Title: Re: Optimising plant fertiliser dosing
Post by: daveyng on April 12, 2018, 09:40:27 AM
I dose Ferts on a daily basis, however, I carry out a daily water change prior to dosing. I do use CO2 and also EasyCarbo which I usually double dose, unless I carry out a major cutback of the plants in the tank, then it’s a standard dose until the growth takes off again. I think my Nymphae Lotus probably utilises most of the Ferts. I throw away a 10 litre bucket of leaves about once a fortnight.
I must admit I do have a lot of fish in my tank, which tends to go against the grain for planted tanks.
Title: Re: Optimising plant fertiliser dosing
Post by: TopCookie on April 12, 2018, 11:19:49 AM
No Matt...  not daily...  I'm still very much in the process of trying to find that right balance of fertilisers...  Switched back & forth a couple of times between TNC Lite & Complete, and have just very recently settled on the Lite - the reason here being no additional phosphates in the Lite, with me having a high phosphate level in the tank...  Weekly dosing is the target, and dosing less than the recommended amount, but still working on how much that should be...  Until recently, almost all of my plants were root feeders, with the exception of the Amazon Frogbit floaters...  The addition of Bucephalandra and even more recently an Anubias, has changed that slightly...  So, still looking to find that right level of both quantity and frequency...
Title: Re: Optimising plant fertiliser dosing
Post by: Helen on April 12, 2018, 04:37:07 PM
A couple points: seeing as this conversation has turned to supplementing planted tanks, would it be a good idea to move it to a new thread in the plants section?  ;)

And, I'm not currently adding anything to my tank at the moment. I've tried a couple doses of JBL ferropol weekly and 24. But that led to outbreaks of blue green and green spot algae. I think the blue green algae (cyanobacteria) was also due to my rotala rotundiflora being a bit overgrown and restricting the surface water flow. I have also tried doses of potassium nitrate (no visible effect) and calcium nitrate (I'm going to try this again to see if I get the same result as last time)

Yes, fluctuating CO2 can be a significant contributing factor to black beard algae (BBA. I have experienced this first hand). But I don't know if this will also apply to liquid carbon.

A recommended dose of TNC carbon for my tank would be 4ml a day (I have about 210l of water in my tank). But I don't even manage to feed my fish every day (I think I break all the 'rules' on routine for fish!  :o) so I don't want to risk having to rely on consistency. And although I'd like my plants to grow a little more, I don't want an explosion of growth that means I have to do lots of plant maintenance. So I was thinking of a 1ml dose every 2 or 3 days.
Title: Re: Optimising plant fertiliser dosing
Post by: TopCookie on April 12, 2018, 06:08:44 PM
Really interesting subject and I agree, this part of the chat probably should be moved to a separate thread...  I can see it being an on-going discussion quite easily... 
Title: Re: Optimising plant fertiliser dosing
Post by: Matt on April 12, 2018, 10:15:32 PM
Voila  :cheers:

Long may the chat continue!...
Title: Re: Optimising plant fertiliser dosing
Post by: daveyng on April 12, 2018, 10:40:45 PM
I was thinking. If you dose liquid carbon, how long does it remain active ? I suppose this would depend on the plant mass and CO2 uptake. Presumably it could be spent in a relatively short time, causing a fluctuation in CO2 levels during the course of the day.
Title: Re: Optimising plant fertiliser dosing
Post by: TopCookie on April 12, 2018, 10:57:11 PM
Isn't dosing carbon actually time sensitive even...?  For example, the way that air stones are best used at night rather than during the day - because gas exchange/flow is different at different points in the day/night...  I really don't know much at all about this, but should do really...!!!

Comes back to air stones and how they figure in that larger picture of oxygen, CO2 and fertilisers for plant health... 

I am tempted by an air stone myself, indeed as a component in that whole picture but also as another possible way to increase surface agitation/movement etc...
Title: Re: Optimising plant fertiliser dosing
Post by: Helen on April 12, 2018, 11:36:16 PM
The principal behind CO2 / oxygen in the water is gaseous exchange. At the surface, where the water meets the air, CO2 passes out of the water and into the air. Oxygen goes in the opposite direction and passes from the air to the water. (Actually, it is a balancing act and the concentrations of both CO2 and O2 balance out across the barrier that is the air/water interface. But the normal concentrations of O2 and CO2 in air and water gives the flows I've described above).

Agitating the water surface increases the surface area of the interface therefore speeds up the flows of gas between air and water.

For a tank that has only fish, which produce Co2 and consume O2, you want to get rid of the CO2 and increase the O2 as quickly as possible, so air stones and increasing surface agitation is preferred.

However, for a tank with a lot of plants, the CO2 that the fish generate during the day will be used up by the plants. At night, the plants stop using up CO2 and produce it. This is why I see the pH in my tank drop overnight (when my tank is correctly balanced), because CO2 reduces the pH of the water. (@Sue has posted the technical explanation for this somewhere). So for a tank with a lot of plants, you don't really want to agitate the surface as it is generally better to keep the CO2 in the water for the plants.

The natural fluctuation of CO2 due to light levels changes is unlikely to trigger BBA on its own. It usually takes an external change to do this. That external influence could be a water change (if the level of CO2 in the tank has got very low) or turning CO2 injection on / off or changing the surface agitation regularly, or turning an airstone on / off. There are also other reasons and these may not trigger BBA.

At the moment I don't have enough fish in my tank to produce the CO2 that my plants would like, so the daily pH cycle isn't quite right. My preferred method for getting the right balance is to increase the amount of CO2 produced by fish (more fish!), also because this is more stable. My aim is to have the right balance between fish and plants so that fish produce all the CO2 that the plants need, no more, no less. But I have a lot of juvenile fish in my tank and what I don't want to do is be overstocked when they've all finally grown!
Title: Re: Optimising plant fertiliser dosing
Post by: TopCookie on April 12, 2018, 11:51:54 PM
Ah, more aquatic pennies drop here...  Thanks Helen...  :)

So, let me run my stocking levels past you...  You've seen the pics of the tank and by now will know that it's set up to be as near low tech as possible, but probably a bit hybrid really, but anyways, here are my creature stock levels in a 170 litre tank: 

12 x Pristella Tetras
11 x Cardinal Tetras
 6 x Red Phantom Tetras
 4 x Corydoras Ornatus
 1 x Lemon BN Plec
12 x Amano Shrimp
 5 x Rabbit Snails
 2 x Faunus "Cappuccino" Snails

I'd imagine that's quite heavily stocked for a 170 litre tank, but there are lots of plants in addition to the canister filter (which is likely to be upgraded soon...

Plant wise, I don't seem to struggle with plants, but this is more by luck than any question of skill or talent...!!!  Only the H.Costata has been troublesome, everything else grows pretty well, including plants that fall into that "medium" category... 

How does that sound from the perspective of balance Helen, with that larger nutrition and gaseous exchange picture...?
Title: Re: Optimising plant fertiliser dosing
Post by: Helen on April 13, 2018, 12:11:38 AM
Have you used the community creator yet? You might have to be a bit creative if your stock choices aren't in the database.

I don't know the particular species you've got (except cardinals) but my gut feel is that you're not as heavily stocked as you think.

(Tips on using the cc: volume should be water volume which is typically 90% of the tank volume)

In it's previous setup, my tank balanced nicely at about 70-80% stocked. I suspect that my stock level to balance now would be higher because I've got more plants. But i also have more slower growing plants than previously, so maybe not.

Anyway, the Cc has me on less than 50% stocked, not taking into account the juveniles, so I'm no where near my balance point yet.
Title: Re: Optimising plant fertiliser dosing
Post by: TopCookie on April 13, 2018, 12:47:51 AM
Just had a quick look and it would appear that I could go to just shy of 100 inches, based on assuming 155 litres of water in the 170l tank... 

Tetras are all up to 2 inches each (x 29 = 58 inches)
BN Pleco up to 5 inches (5)
Corydoras up to 3 inches (x 4 = 12 inches)

Not 100% sure how snails and Amano shrimp fit into this equation...  They obviously do contribute to the overall bio load by virtue of being living creatures, but I believe it's a lot lower with snails & shrimps...?

So, it would appear that I could have potentially 20+ inches of potential remaining...  Just enough for some Kuhlis, eh H...   ;D
Title: Re: Optimising plant fertiliser dosing
Post by: Matt on April 13, 2018, 06:17:51 AM
@TopCookie Please see http://www.thinkfish.co.uk/article/community-creator (http://www.thinkfish.co.uk/article/community-creator) for more info on the community creator which Helen was referring to.
Title: Re: Optimising plant fertiliser dosing
Post by: TopCookie on April 13, 2018, 10:34:15 AM
My search took me here:  http://www.thinkfish.co.uk/calculators/stockinglevel 

Your link shows me a how to use the community creator diagram, but I can't seem to find the actual calculator Matt...?  Can you link me in to where it is please...?

Edit:  Just found it...  Had to click on a fish species to get there - the links labelled "Community Creator" don't actually take you to it, oddly... 
Title: Re: Optimising plant fertiliser dosing
Post by: TopCookie on April 13, 2018, 10:52:53 AM
Interesting... 

Had all species with one unsurprising exception; the Corydoras Ornatus...  They are roughly the same sort of size as Sterbai...  So, I used Panda Corys in the calculator but doubled the number from x4 to x8...  This gives me the following results based on the actual tank size (as opposed to probable water amount)

(https://imagez.to/i/yq7Z8eps.png)
Title: Re: Optimising plant fertiliser dosing
Post by: Littlefish on April 13, 2018, 12:26:48 PM
You'll find more species available here http://aqadvisor.com/
It's stricter than the CC here, and it's worth double checking stock levels and compatibility on this one.
Title: Re: Optimising plant fertiliser dosing
Post by: TopCookie on April 13, 2018, 12:37:34 PM
Thanks Donna, and will do...  :)
Title: Re: Optimising plant fertiliser dosing
Post by: fcmf on April 13, 2018, 01:59:42 PM
You'll find more species available here http://aqadvisor.com/
It's stricter than the CC here, and it's worth double checking stock levels and compatibility on this one.
It's actually less strict for me ie would "allow" me a third shoal whereas our CC wouldn't.
Title: Re: Optimising plant fertiliser dosing
Post by: Matt on April 13, 2018, 11:01:15 PM
The major difference is the selection of an external filter on the community creator means you are suddenly allowed 60 % more stocking than normal. Personally i dont think this is realistic and always stick on oversized internal.. allowing me 20% more stocking for having a great filter.... much more realistic.
Title: Re: Optimising plant fertiliser dosing
Post by: Helen on April 13, 2018, 11:44:55 PM
I use the external filter setting, with the 60% extra capacity. I'm happy doing this because I have so many plants in my tank which significantly increase the CO2 / O2 exchange and use up nitrates and phosphates.

But I also try to choose fish that swim at different levels and am therefore conscious of how many fish I have at each level. At the moment I have dwarf rainbow fish, which are surface swimmers (top third of tank), rasboras which are middle swimmers, fiveband barbs swim in the bottom third and kuhli loaches which are substrate dwellers. (I also have a BN Plec, who is outside the layers, but who  is also pretty messy) The fish don't always stay in 'their' areas, but by planning my inhabitants  by their swimming behaviour, I find I don't really have empty parts of the tank when other parts are really busy (except occasionally, like feeding time). This is also why I don't have as many fish as I'd like at the moment because I've planned my inhabitants and am struggling to vary the plan without breaking my layers concept. At the same time as choosing fish suitable to my water parameters.

The cc is a guide. It'll take a bit of practice, but you will learn how you need to adapt it to fit your tank parameters.

Also, I've yet to find a guide that takes into account the beneficial effects of live plants in the tank.
Title: Re: Optimising plant fertiliser dosing
Post by: TopCookie on April 14, 2018, 01:39:39 AM
Also, I've yet to find a guide that takes into account the beneficial effects of live plants in the tank.

+1 on that point...!!!  It's a shame though, as they do consider plants as virtually acting like filters, so I would imagine that having lots of plants must surely make quite a considerable difference...?
Title: Re: Optimising plant fertiliser dosing
Post by: Matt on April 14, 2018, 06:18:19 AM
+1 from me too

My reasons are more aesthetic and welfare related... I am always conscious that I am a zoo keeper in this hobby and overfilling a small cage of animals is something I'm very conscious of not doing.... I have never been beyond 85% stocked when internal filter is selected. The tank also starts to look very full to me by this point. In fact im only at 60% now and my plans take me to 70%.

I'm not claiming my fish are necessarily better looked after than anyone else's here by the way, just that I strive to make sure they have the best possible lives as we all do and this is something that matters to be... I have no idea if it matters to the fish in reality!

I feel like I've had a rant here which was not my intention... Just sharing my theories on things  :)

+1 on the layers thing also @Helen for the same reasons. I love bottom dwellers but always need to be careful that I have something for the top of the tank too or that would be wasted space and the bottom would be like a war zone with everyone struggling for territories etc.
Title: Re: Optimising plant fertiliser dosing
Post by: Helen on April 14, 2018, 08:39:46 AM
I was originally against keeping fish as I thought it cruel to contain a creature when in nature they have so much space. Then I spent a couple months scuba diving as part of reef conservation and watched fish (albeit marine) in their natural environment. And I realised that small fish don't know that they have so much space because they stay in a relatively small area. That was when I thought it might be nice to keep fish at home. So I looked to set up a micro environment. I originally wanted a south east Asian biotope, and chose plants and fish to suit. But I think that was perhaps a bit too ambitious for a newby fishkeeper, so I've gradually relaxed the boarders. Most of my fish and plants are Asian, but I've got the odd exception - Bertie my BN. But my aim is to still to create a micro environment where the fish and the plants balance each other for needs and clean up.

It took a while to find the balance, but I have since made major changes so I'm still in the process of working out what that new balance is. And it's not a static target, due to fish and plants growing, some of my fish are old aged so I am expecting deaths before I find my new sweet spot. I've not had any babies (in the tank!) yet, but that would also change the balance.

I used to think of 3 layers in the tank - top middle bottom. But since adding my fiveband barbs I've realised there is another layer, non benthic (free swimming) fish that live in the bottom third of the water column ie near the substrate but not on it. I've not yet worked out how that will affect the overall balance / aesthetic 'fullness' of the tank.

It's also worth remembering that we judge stock levels by fish length, but that isn't necessarily the best reflection of the effect a particular fish will have on the tank.

For example I have a BN Plec whose calculated size is 12cm. And kuhli loaches whose calculated size is 10cm. Their contribution to the balance in my tank is wildly different. Bertie is far more messy than his calculated stock size (even though he's an algae eater). A pair of BN Plecs is probably the most that my tank could sustain (24cm). But my kuhlis are long and thin and are more clean up crew than mess contributor. My tank could probably comfortably sustain about 15 if I didn't want any other benthic fish (150cm).

So there is a lot more to consider when finding the right stock for a particular tank than just the calculated stock %. (Which is why it is heavily emphasised that it is just a guide).

Ps @Matt I didn't read your post as a rant at all! Didn't consider it might be until you mentioned it.  ;)
Title: Re: Optimising plant fertiliser dosing
Post by: Sue on April 14, 2018, 12:19:47 PM
On the subject of the CC and filter type, increasing filtration does not increase the amount of fish you can keep, provided the filter is adequate for the size of tank. I suppose that you could say that an external effectively increases the volume of water by the amount of water inside the body of the filter but that is not much.

I think the basis of the CC saying that you can have more fish with increased filtration is old thinking. I joined the old incarnation of Thinkfish in 2006 and the CC said back then had tiers of filtration allowing for increasing stocking levels.
Stocking is now all about the size of the tank a species needs, the numbers a particular species needs etc. It is now known that doubling the shoal size of small tetras, for example, does not double the shoal's bioload because more numbers means less stressed fish, and the more stressed a fish is, the bigger the bioload.


It is my opinion that we should ignore the filter type and always select internal filter.
Title: Re: Optimising plant fertiliser dosing
Post by: Helen on April 14, 2018, 06:42:09 PM
Do you mean just use the standard internal filter on the CC, @Sue  and not the oversized internal?

Under the old thinking, why does a bigger filter mean more fish? Is it purely because of the ability to hold more bacteria?

I reckon my external filter holds about 2 litres of water. Which in 220l is negligible.
Title: Re: Optimising plant fertiliser dosing
Post by: Sue on April 14, 2018, 06:55:48 PM
Yes, I use 'standard' internal in the CC.

I've never understood why a larger filter was said to mean more fish allowed. The article on here says that larger filters can process more waste but I don't think this is true. Provided there are enough bacteria in the tank to 'eat' the ammonia made by the fish, and the nitrite made from that ammonia, filter size doesn't matter. The 'filter' bacteria live all over the tank not just in the filter. And of course there are countless other species of micro-organism that play their part in tank maintenance which live in the substrate.
The article on here says that a large external can process many times more waste than a standard internal. How?
The articles on here were written at least 12 years ago, probably more. Our understanding of what goes on inside a tank had leapt forwards a lot since then.

It is possible that the idea arose because the larger the filter the more flow there is, and more flow usually goes with better oxygenation of the water because it churns the water up better. And from there it was not a big leap to saying a large filter could process more waste.

Title: Re: Optimising plant fertiliser dosing
Post by: Helen on April 14, 2018, 07:29:54 PM
If I switch to an internal filter, my current tank capacity changes from from 46% to 74%.

But, I could double the number of rasbora I have and not increase the bioload.

If I add a new shoal of small fish, then I clearly would be increasing the bioload. But would any of the bioload be 'compensated' for because I already have shoaling fish?
Title: Re: Optimising plant fertiliser dosing
Post by: Helen on April 14, 2018, 07:36:20 PM
If the very original calculation was based on water surface area, increased circulation from an external filter would increase the relative surface area in terms of how much interface there is for gaseous exchange. Perhaps that's where it comes from?

What sort of effect on stocking capacity do you think planting is going to have? I would have thought it'd increase it, because the addition of plants does increase the waste removal.
Title: Re: Optimising plant fertiliser dosing
Post by: Sue on April 14, 2018, 07:39:53 PM
Yes it would. The more members of a shoal of a given species, the 'happier' they are. It is when fish are less 'happy' ie more stressed that they add more to the bioload. But that doesn't mean you can go mad and add a few hundred fish  ;D

And it only applies to small shoaling fish.


Yes, plants do increase water quality. With enough plants you don't actually need a filter  :o
I live on Teesside, home to a very large chemical industry which was once almost all owned by ICI. They pioneered the use of reed beds to clean industrial waste water before it was returned to the river.
Title: Re: Optimising plant fertiliser dosing
Post by: Andy The Minion on April 14, 2018, 09:21:16 PM
I have to admit to having been in both camps on the fish stocking discussion. When I started with a 200 litre tank I was discovering desirable fish around every corner. I found an article on stocking that made the argument that the 'historic' (1960's) stocking level that arrived at the original 1" per gallon or sq ft of surface area were based on gassious exchange at the surface in tanks that only ever had under gravel filters that also created adgitation at the surface. The logic went that this covered all of the 'other areas' for bacteria to colonise that modern tanks still have but the inclusion of pumps and porous media in filters provided more efficient convention and could therefore be factored into the biological processing area. Well this suited me at the time and I gradually increased my filter capacity and ended up with an external and took the 1.8cm/litre as the tank limit.
In practice I didn't I ever got there, I think I maxed out at 1.5cm/litre because the water tests were pushing me to twice weekly changes based on the rate of Nitrate increase and I could see it wasn't a sustainable level if I wanted low Nitrates.
However..... I still much prefer externals and wouldn't ever stop using them. Like the general vibe in the thread I don't use them to overstock although I do a proper measurement of water volume and include them in that. They don't reduce work either, I pre filter them so they don't accumulate gunk, I just like the fact that I can massively over specify the biological capacity. At work I would call it a large factor of safety for the bacteria - it just feels to me like the right thing to do.
Incidentally the argument that the surface area increaes if the water surface is agitated doesn't doesn't sound correct, it's more likely that the flow that is causes the agitation is exchanging the water in contact with the air constantly so a pump outlet angled up towards the surface that just ripples will be quite adequate.
Title: Re: Optimising plant fertiliser dosing
Post by: TopCookie on April 15, 2018, 11:47:30 PM
Yes, I use 'standard' internal in the CC.....

Ah, what you say Sue certainly makes sense...  Just by judging on the level of detritus/mulm in the tank, that would suggest that in my set up, I'm far closer to being fully stocked than the CC suggests - especially with the external filter option selected...!!!

With this option, CC tells me 49% stocked, although I would immediately have to allow more on the grounds of having to substitute the Corydoras (even after fiddling numbers as best as possible)...

Switching to the "Internal" filter option gives me 79% stocked and actually a much more believable & logical figure... 

This still allows me to add just a few fish though, which is nice, and in the relative confidence that this should not present a problem if any new additions are picked wisely...  :)