Osmocote Experiment

[Corbidorbidoodle]

So, this is just sort of a PSA/learn from my mistake.

I set up a couple of new tanks just for experimenting. Various scaping and whatever. One I bought plants for and the others just plant trimmings. Since I've seen people make DIY root tabs using Osmocote, I thought I could just sprinkle some on the bottom of the tank before I put in the substrate. I'd say I put in about 10 tabs worth.

Now, after a few weeks, the moment I dip a test strip, the Nitrite and Nitrate pads go instantly bright fuchsia! There's so much nitrite!

Weirdly, there's no Ammonia. Also, the lower tank has a bunch of guppy mutts and low grade cherry shrimp. They're both doing great. Guppy babies and everything.

I'm gonna scrap both tanks this weekend and start over. Is it possible to use Osmocote this way? Did I use too much? Not enough substrate?

I'm wondering if, for this to be effective, maybe I'd need regular sand rather than pool filter sand to cap it properly. I'll probably just go regular substrate when I set them up this time. No need for me to get fancy.

[Fish Folk]

I know aquarists who have done this. I think the fertilizer adds straight nitrogen-compound / nitrate. It is not the nitrogen cycle, so ammonia won’t register.

You need TONS of plants to absorb this amount. Cover it completely. Like this tank here…

 

[nabokovfan87]

Kind of similar to my issue trying to cap something with sand for the first time. You need 2-3" from what I found out.  Likely 3-4 inches to cap it depending on flow in some spots and the sand moving slightly. 

It ended up in my case with the planted substrate just mixed all over the place in the sand and when I moved the tank it all got trashed. 

From your photo some parts are very thin, others maxing at what looks like 3/4-1".  You might get away with adding way more sand and some carbon for a week or two.

[Tihshho]

I've used the process you described before with a ton of success in the past. As FishFolk stated, the Nitrogen compounds released are the key features of what is being provided as a food source for the plants. When you use a base layer, you need to be sure to plant the tank accordingly so that the nutrients are being taken up and not just released into the watercolumn as part of a food source for the beneficial bacteria and/or being pulled out during water changes. Getting the planting done heavily will help counteract the high readings, but having high nitrogen sources isn't a bad thing as long as plants are able to use it. If it gets to the point you're nitrogen levels are so high, you have high phosphates, and your plants cant' keep up you'll be battling different annoying algaes. 

[Seattle_Aquarist]

Hi All,

In 2019 after the AGA International Convention where I heard a presentation of the possible negative effects of water column dosing on certain species of aquatic plants (Lythraceae family: Rotala species, Nesaea species, Cuphea species)   I also decided to try Osmocote Plus as an experiment using them as the primary source of macro-nutrients for a tank (N,P,K).  First of all about over 50% of the nitrogen in Osmocote Plus is in form of ammoniacal nitrogen (aka ammonia) so it can be very toxic to animals, cause algae outbreaks, as well as cause 'plant burn'.  Also it is important to note that the product contains no secondary nutrients (magnesium, calcium, sulfur) nor any micro-nutrients (iron, boron, manganese, zinc, etc) so it is not a 'balanced' fertilizer.  Also, this product is not made to be used in water and the release of nutrients is faster as a result.



I did a lot of reading before starting this experiment and learned that placing the Osmocote Plus DIY tabs at the bottom glass with a minimum of 3" of substrate above them helps to minimize the amount of ammonia that leaches into the part of water column where the fish are located.  I went with 2-1/2" of high CEC substrate (Safe-t-sorb) and followed the recommendation of one size "00" gel cap spaced 6" apart which resulted in 21 tabs in the 45 gallon tank.  The result after carefully filling was high ammonia level showing up within a couple of days.  This required me to do 50% water changes 2-3 times per week for about  a month to keep ammonia levels minimized.  My conclusion was that was way too many tabs!  lol

How did the plants do?  Here is a picture of the 45 gallon tall tank two weeks after planting:


And here it is about 2 months after planting (Rotala species @ arrow):


In the last 2-1/2 years I have set up three tanks with DIY Osmocote Plus root tabs as the primary source of nutrients and this what I have learned. 

First of all start with one size "00" root tab per 10 gallons of tank volume.  Root tabs seem to drop in nutrient release after five weeks so that is when I add root tabs again at the same dosing level.  Getting these tabs to the bottom glass once everything is in place was a hassle.  First of all the gel caps dissolve very quickly so there is little time to get the tabs in place and forceps didn't get the job done.  Also, I try to place the tabs away from the base of plants to avoid root burn from the ammonia.  I have found the following to do a good job of getting the gel caps down to the bottom glass:



Secondly, the root tabs need to be augmented with a good source of micro-nutrients - I use Seachem Flourish Comprehensive dosed at 2 ml per 10 gallons (about 2 times recommended dosage).  I also dose calcium sulfate and magnesium sulfate to provide the needed secondary nutrients (Ca, Mg, S). 

I still do 50% weekly water changes on my tanks but I have found that the amount of algae I have do deal with on glass or plants less than it was when I did water column dosing.  Also, I only have have to dose my micro and secondary nutrients once a week so my dosing time is drastically reduced.  And my plants seem to do just fine with dosing nutrients in the substrate, including Anubias and Microsorum attached to the hardscape.  -Roy
45 gallon in March, 2022

Edited April 25, 2022 by Seattle_Aquarist

[Cory]

@Seattle_AquaristAre any of your tanks still running undergravel filters with the plants? I'd love to see a write up similar to your experience with the osmocote tabs but on planted tanks and your undergravel findings.

[Seattle_Aquarist]

Hi @Cory,

Most folks  on this forum (thank you btw, very good forum) don't know that at one time I used undergravel UG) filters in all my planted tanks with good success. 

When I transitioned to using root tabs that contain ammonia I ceased use of undergravel filters.  A UG filter draws the the water from the substrate surface through the substrate to the area of the root tabs (where the concentrated ammonia is) and then up the output tubes of the UG filters.

Ceasing the use of UG filters started my search for good filtration alternatives - long story short.  After trying several brands (but not all - lol) I have decided on the Fluval 07 series of canister filters and the Hagen HOB Aquaclear filters.  Why?  First they are quiet.  Second they are reliable.  Third they have good media availability.  Fourth, when you need parts (and eventually they will all need parts like impellers, impeller shafts, internal trays, etc) they can be found relatively easily (unlike some brands).  Fifth, they have a good warranty backed by a well established company and an (800) number for service support.

You may remember an article I did for the GSAS newsletter where my 2 year + 10 month old Fluval 2.0 died.  It had a 3 year warranty.  I contacted Fluval Customer Service, gave them the purchase information and sent the old 36" fixture with a copy of the receipt to them.  One week later a new Fluval 3.0 was on my doorstep.  That is the type of service that keeps customers coming back.  -Roy

[Torrey]

On 4/22/2022 at 6:05 PM, Corbidorbidoodle said:

So, this is just sort of a PSA/learn from my mistake.

I set up a couple of new tanks just for experimenting. Various scaping and whatever. One I bought plants for and the others just plant trimmings. Since I've seen people make DIY root tabs using Osmocote, I thought I could just sprinkle some on the bottom of the tank before I put in the substrate. I'd say I put in about 10 tabs worth.

Now, after a few weeks, the moment I dip a test strip, the Nitrite and Nitrate pads go instantly bright fuchsia! There's so much nitrite!

Weirdly, there's no Ammonia. Also, the lower tank has a bunch of guppy mutts and low grade cherry shrimp. They're both doing great. Guppy babies and everything.

I'm gonna scrap both tanks this weekend and start over. Is it possible to use Osmocote this way? Did I use too much? Not enough substrate?

I'm wondering if, for this to be effective, maybe I'd need regular sand rather than pool filter sand to cap it properly. I'll probably just go regular substrate when I set them up this time. No need for me to get fancy.

I have sprinkled straight osmacote in the bottom, *under* 1" (front) to 3" (back) or *more* substrate. It also requires (as FishFolk said) a lot of plants.

I will put osmocote in my bare bottom plant tubs, for speeding up propagation of cuttings under bright shop lights, no problems. Just drop an airstone in there, and wathc  the roots grow like crazy. I also make my own osmocote root tabe, to put under heavy feeders when I either can't afford/ am waiting for delivery of new EG Root tabs. 00 gel caps will fill with the exact right amount for a square foot of tank to be well fertilized, as long as I remember to squeeze the air out first so it doesn't float when the Malaysian trumpet snails decide to practice their (re)landscaping skills and excavate the gel cap (they also escavate the osmocote from time to time. I found mixing it in bentanite clay protects the tank better than airfilled 00 gel caps....)

The nitrites and nitrates from the osmocote are sufficient to give fish gill burns, which is why I prefer the EG tabs. However, I buy in bulk😅 Therefore, I probably wouldn't run out of osmocote for at least 2 more years if I hadn't found ACO, and at my current rate of use (osmocote as a stopgap) I probably have a 10 year supply left.😂

[gardenman]

I come from a gardening background and should point out that there's more than one kind of Osmocote and each has a somewhat different formulation. I believe they make somewhere around ten different formulations that I'm aware of. So Osmocote used by one person may not be the same Osmocote as used by another. 

[Torrey]

On 4/26/2022 at 7:58 AM, gardenman said:

I come from a gardening background and should point out that there's more than one kind of Osmocote and each has a somewhat different formulation. I believe they make somewhere around ten different formulations that I'm aware of. So Osmocote used by one person may not be the same Osmocote as used by another. 

Good call @gardenman. I bought the Osmocote Plus, based on research of what our water supply is low on, and the success of a few fellow NMAS members had with the slow release granules, even in their shrimp tanks.

[Corbidorbidoodle]

Okay, soooo...

Turns out everything is good. Great, really. I just didn't give the tank long enough to cycle. I'm terrible with estimating time. I don't think it had been very long, but I thought it was at least a month. But now everything is settled in and the readings are great.

0 Amonia, 0 Nitrites, like, 10-20 Nitrates. It's going better than root-tabbed substrate. I can't even keep 10 Nitrates in those tanks. Stuff is starting to grow really well in these new tanks.

Oh, and I used "Osmocote Plus". I've seen a bajillion people online using that stuff for their DIY root tabs. I should have been more specific about that.

So, I guess the experiment was a success!

[Torrey]

On 4/29/2022 at 10:39 AM, Corbidorbidoodle said:

Okay, soooo...

Turns out everything is good. Great, really. I just didn't give the tank long enough to cycle. I'm terrible with estimating time. I don't think it had been very long, but I thought it was at least a month. But now everything is settled in and the readings are great.

0 Amonia, 0 Nitrites, like, 10-20 Nitrates. It's going better than root-tabbed substrate. I can't even keep 10 Nitrates in those tanks. Stuff is starting to grow really well in these new tanks.

Oh, and I used "Osmocote Plus". I've seen a bajillion people online using that stuff for their DIY root tabs. I should have been more specific about that.

So, I guess the experiment was a success!

Yup, been there done that!

Which is why I now have a spreadsheet that keeps my data for me... like setup date, etc.

Which really paid off when I had my surgery, and when I had my stroke last year! Easy to catch fluctuations if I am not relying on memory.