Do I Even Need Ferts?

I have just started up yet another aquarium, a 10 gallon with live plants. Over the summer, I had great success with a 5.5 gallon tank using soil capped with gravel. I decided to use Caribsea Eco-Complete substrate this time around. In my 5.5, I didn't need to add any ferts because the soil provided all the nutrients my plants could possibly need. Eco-complete apparently contains nutrients such as iron, magnesium, and potassium, but I'm wondering if additional ferts are necessary. I'm not growing anything demanding, just standard fare for a low tech, low-to-medium lighting setup.

 

Eventually those minerals will be spent, so yes you'll likely have to add ferts in. But That could be a few years.

 

Eventually those minerals will be spent, so yes you'll likely have to add ferts in. But That could be a few years.

Should my water column feeders be okay? I've got some anacharis and anubias in there, I know that they draw nutrients from the water rather than directly from the substrate.

 

Eco-Complete is actually completely inert from what others have reported over at planted tank and thebarrreport.com. The advertising is highly misleading as the listed nutrients are simply part of the chemical structure of the substrate and biologically unavailable to plants. A bit like claiming you can breathe sand because silicon dioxide has oxygen in it.

You'll definitely need ferts. NilocG Thrive (either S, C or any of the variants thereof) is my usual recommendations because the guaranteed analysis is quite useful and you can buy more concentrated solutions of it.

 

What about dry ferts like the Green Leaf EI kit? Is this overkill for a 10 gallon, or even a 20 gallon lightly planted tank? I've been using Flourish root tabs and Excel and the plants seem to be doing fine, but these are expensive and I'm looking for a more economical and complete fert. Plus, I'll be building a planted 70 gallon pentagon in the near future, so I definitely need to switch to dry ferts for that tank.

Still confused on whether to use the PPS or EI kit. Does it depend on the plant species, or is this something that needs to be experimented with? Once I start using dry ferts, do I continue to use root tabs and Excel? Is CO2 injection absolutely necessary when using ferts? I planned on adding a CO2 system on my 70 gallon, but not on my 10 or 20.

 

The Green Leaf EI kit is excellent. It's likely far more economical than the Thrive solution.

No it isn't overkill at all. Many people run EI dosing on smaller sized tanks. To make it easier to dose smaller quantities of dry ferts in 5-20 gallon tanks, I'd advise you to pick up a miligram scale and a few 300-500 mL pump bottles to make DIY solutions.

Example: Rather than having to measure out a minute 90 mg of KH2PO4 (which can more-or-less be blown away by breathing) for a 10 gallon tank, you can dissolve 3.01 grams in 500 ml of distilled water to make 15 ml doses (500ml will last a little under 3 months).

The benchmark ppm targets for EI dosing (as listed on the various sources and at the nutrient calculator at rotalabutterfly.com) are based on high lighting and 30 ppm CO2. But the usefulness of EI is that it's highly adaptable and the benchmarks can be decreased in response to no CO2/lower light.

For example, many people with low light/no CO2 often dose 1/3rd of the recommended targets. So rather than 1.3 ppm KH2PO4 three times a week with a 50% water change weekly, they'll instead do 1.3 ppm KH2PO4 once a week with a 10-25% water every weekly/fortnightly. It's all about experimenting and adapting the doses in response to plant growth.

Is CO2 absolutely necessary? No, it isn't. But it's important to note that plants comprise 60-70% carbon, and latent CO2 concentrations in water are quite low, about 5-10 ppm, compared to atmospheric CO2 ppm at 300-400. Some plants only thrive in a tank with high CO2, and likewise, if your light system is of sufficient intensity, then it'll nearly always require injected CO2 in order to prevent algae blooms from occurring if dry ferts are dosed at their benchmark targets.

The choice between PPS-Pro or EI dosing is, in many ways, a personal decision. For whatever reason, it seems that more planted tanks use EI (at least, there's more resources around it) and that's it's the method I follow.

 

Thanks for the detailed reply! I don't want to inject CO2 on either the 10 or the 20, and already have some algae issues in the 20. Plenty of light in the 20 (using an Aqueon Optibright 30" LED fixture) That being said, what would you recommend to keep the plants happy and algae to a minimum? And I would think aquatic plants are adapted to the much lower concentrations of CO2. I'm guessing it's the atmosphere we put them in (an enclosed tank) that necessitates the need for us to inject? Does having a lid on the tank further necessitate the need to inject? I don't plan on removing the lids; I'm just curious.

 

I'd recommend picking up the Green Leaf EI kit. If you'll be dosing EI further down the line on a 70 gallon tank, you might as well prep now and become familiarised with the process.

Start with 1/3 doses and examine the effects over a month. Too much algae? Reduce the photoperiod to 6 hours or so and continue observing. Another effective method of reducing light intensity is to raise the height of the light to reduce the amount of radiation available to the plants.

I realised I had forgot to answer your question about root tabs and Excel. Generally, if you inject CO2, you don't bother with Excel. Some people do use Excel with CO2 purely on account of Excel's algaecidal effects in order to keep any latent algae at bay. But I find it's a bit of a waste of money as it's easier (and far cheaper) to spot dose algae with a 3% hydrogen peroxide solution. But I would recommend using Excel as a substitute carbon source if CO2 won't be injected.

Root tabs are more of a supplement to water column dosing than a complete replacement. Tom Barr (the developer of EI) often cites research indicating that plants don't particularly show a preference for nutrient uptake via substrate roots or via the water column (through aerial roots and leaves): they'll take up nutrients wherever they occur.

Many, such as myself, don't use root tabs at all. Some do. But it's worth pointing out that most root tabs on the market (e.g. Flourish and API root tabs) only supply micronutrients and lack any substantial amount of nitrogen, phosphorus or potassium. Some aquarists make their own root tabs using Osmocote Plus and gelatin capsules.

I'm not sure of the comparative difference between natural ecosystem CO2 ppm and aquarium tank CO2. Most of the CO2 found in aquatic ecosystems tends to be the result of decomposing organic matter, but given that we vacuum the substrate and remove decaying matter so frequently in tanks, this isn't likely the primary cause for aquariums. It's more likely to be fish respiration, but I can't imagine that'll account for much. It's unlikely lids will have much of an effect due the high rate at which gases diffuse across connected volumes.

It's true that many plants grow without injected CO2, but it's often to a slow degree or with particular forms of growth that people don't find especially appealing. Usually that rapid, lush, green look can only be achieved when CO2 is presented in luxurious supply for plants to use.

 

It's completely inert?! You gotta be kidding me... is there a substrate you'd recommend that actually has nutrients in it?

 

It's completely inert?! You gotta be kidding me... is there a substrate you'd recommend that actually has nutrients in it?

ADA Aquasoil, Marfield Controsoil, Tropica Soil, Dennerle Soil if you can find it, and to a lesser extent Fluval Stratum.

 

Sheesh. I've never seen any of those at any store... guess I'll just have to do ferts. >__>

 

Sheesh. I've never seen any of those at any store... guess I'll just have to do ferts. >__>

You can find them online, but they cost more than the average inert substrate. With ferts, the EI method discussed above will more than make up for the substrate

 

Next time I think I'll just go with dirt capped with sand or gravel, haha... I know almost nothing about ferts and I don't want to turn my dorm into a chem lab just for DIY solutions, ugh.

 

Next time I think I'll just go with dirt capped with sand or gravel, haha... I know almost nothing about ferts and I don't want to turn my dorm into a chem lab just for DIY solutions, ugh.

Maybe this can help a little:
Info Before You Buy Flourish And Ferts In General

 

Considering I recently put root tabs in both tanks, should I only dose the macronutrients until the root tabs have dissolved? Think they last a few months

 

Next time I think I'll just go with dirt capped with or , haha... I know almost nothing about and I don't want to turn my dorm into a chem lab just for DIY solutions, ugh.

Substrate is one of those really personal decisions I find. There's nothing inherently wrong with Eco-Complete, I used three bags of it in my 47 g. I personally can't stand the small spherical pellets of Aquasoil (which look like baby rabbit droppings to me).

A lot of people prefer Aquasoil, this is true. But like any substrate, it does have its disadvantages: (1) depending on how heavily planted the tank is, the nutrient capacity within the soil might be used up in as little as 2-3 months; (2) it tends to turn into a muddy slurry over time (usually takes a few years) and this causes turbidity issues when disturbing the substrate.

Usually the long-term benefit of a soil substrate (like Aquasoil) is the cationic exchange capacity (CEC): the ability to bind nutrient cations in the water closer to the substrate and closer to the root system. Generally this isn't a huge benefit if you're regularly dosing your water column with ferts (and plants don't show a particular preference between nutrient uptake via the water column or via the substrate), but many nutrients do eventually precipitate into forms that aren't readily available for uptake by plants. Many (if not all) plant species secrete enzymes from their root systems that allow them to reduce these precipitates (if they're bound by the substrate close to the roots) into forms that are biologically available to plants.

But even inert, low-CEC substrates like Eco-Complete (and gravel in general) can accumulate a higher CEC over time as a layer of mulm (decaying organic matter) settles on top of the substrate.

Considering I recently put in both tanks, should I only dose the macronutrients until the root tabs have dissolved? Think they last a few months

I'd dose macros and micros. The difficulty is gauging the rate of dissolution of root tabs and the quantity of micros being made available for plant uptake. This is one of the general challenges of using root tabs (which is a major reason why I don't bother since I do full EI dosing).

 

Welp, after some research I have decided to buy a bottle of Easy Green from Aquarium Co-op. I know dry ferts are cheaper and whatnot but the plants I got aren't highly specialized and I'd rather get into this when I'm home.

 

That's fine! The savings over the short-term for using dry ferts in a smaller tank aren't very much over the short-term. Maybe $20 or so per year.

 

What's so special about the Easy Green that it only requires one dosage per week, whereas most dry ferts are to be used daily?

I switched from gravel to sand in my 20 long because I have Corys, and my plants aren't growing as quickly as they do in the 10 gallon, which has coarse gravel. It's not yet clear if the substrate is the cause or if it's a lighting and/or fertilizer imbalance. The 20 long has a relatively powerful light (30" Aqueon opti-bright) and the 10 gallon has what came in the kit (6 white LEDs). Even with the low light, the S. Repens are doing very well. Significantly better than the ones in the 20 long are doing. My best guess is I need more fertilizer in the 20 to match the lighting or cut back the lighting (current photo period is about 10 hours/day), although I'd rater increase the fertilizer, if that is in fact the restriction. My Amazon Swords are doing well and my Anubias Nana have sprouted new growth over the past two weeks since I added root tabs, but the S. Repens aren't really taking off like they are in my 10 gallon (they were planted at the same time).