Low-Tech Excel based Planted Aquariums: A Guide

Non Co2 Low Tech Planted Tank

Before reading this article, I would highly recommend that you read the article on Low-tech, Non CO2 tanks. That article introduces the concept of low-tech tanks and explains in detail the science of low-tech, non CO2 tanks along with some guidelines for maintaining such tanks successfully. One of the drawbacks of this low-tech method is that plant growth can be fairly slow compared to growth rates seen in CO2 enriched tanks. On the other hand, tanks with pressurized CO2 require you to invest a fair bit of time and money to keep them in shape. The balance between lighting, nutrients and CO2 in these tanks is much more delicate and there is a lot less room for error. Any imbalances in the tank can quickly lead to a massive algae bloom. This article details a middle ground between these two methods wherein Seachem's Excel is used as a source of carbon in the tank.

Seachem Flourish Excel

Seachem Flourish Excel

What is Excel and what does it do?

The active ingredient in Seachem Excel is Polycycloglutaracetal. It is a clear liquid which is quite toxic. Be careful when handling it and make sure to avoid skin/eye contact. Essentially it is a Carbon compound which is assimilated by the plants and used by them during photosynthesis. In this manner it acts as a carbon source and a replacement for CO2 in planted tanks. However the uptake of Excel is not as much as dissolved CO2 in tank water. In lay mans terms, it takes "more work" for plants to use Excel as a carbon source than it does to use dissolved CO2 directly from the water. As a result, while Excel does boost plant growth in comparison to Non CO2/Non Excel methods, the growth rates will still be slower than in CO2 enriched tanks. Also note that Excel has a half life of 11-12 hours so it is not active in your tank beyond 24 hours. This is why daily doses are recommended. Also make sure to dose it before your light come on in the tank. Excel is light sensitive so make sure to store it in a dark bottle if you plan to pour it out of the regular bottle.

Advantages of using Excel:

1) Faster plant growth as compared to Non CO2, non Excel, low-tech tanks.
2) Excel is known to act as an algaecide. Many people dose excel in their tanks when they are battling algae and have had great success. What this means is that the daily dosing of Excel will act as a deterrent to algae. This is great news for anyone starting out with their first planted tank.
3) Much easier to use in comparison to setting up a CO2 system.

Disadvantages of using Excel:

1) Excel works great for smaller tanks but it can get pretty costly for larger tanks.
2) Some plants which do not have stomatas cannot be grown with Excel. This includes plants such as riccia, vallisneria, egeris densa, hydrilla and liverworts.
3) Excel is toxic. Be careful when handling!
4) Fertilizing is a must for a healthy tank.

What changes when you use Excel in your tank?

Here I'm going to talk about what you need to do differently in comparison to Low-tech, Non CO2, Non Excel tanks as described here. The main effect of adding Excel is that you boost plant growth rates. As a result it also causes a larger demand for nutrients by the plants. The availability of a carbon source allows us to increase the lighting levels by a bit in comparison to non excel tanks. I will list the changes that need to be made in comparison to the guidelines for non excel tanks.

Lighting: Lighting can be pushed upto 2.5 watts per gallon (wpg) at max. You probably don't want to go any higher than this. As before, in the case of spiral CFLs you could probably go up to 3 wpg due to their inherent inefficiency. With T5 tubes you should probably stick to 1.5-1.75 wpg. If at any point you see signs of algae (assuming you are dosing ferts normally), then you should immediately lower your light levels/lower the length of photoperiod or do both. Remember that playing it safe with slightly lower lighting is always a wise choice as you will have less trouble with algae on the whole. Also remember that for tanks smaller than 10 gallons, the wpg rule breaks down. You'd probably need 5-6 wpg for tanks that are 5 gallons or smaller.

Dosing fertilizers and Excel:
A 20 gallon tank using excel should get:

1/8 teaspoon of KNO3, 1-2x a week
1/16 teaspoon of KH2PO4, 1-2x a week
2mls of Seachem Flourish, 2x a week
SeaChem Equilibrium 1/8th once a week (Immediately after weekly water change)
50% weekly water change
Dose 1-1.5x the recommended dose for Excel (1 ml for every 10 gallons on a daily basis and 5ml for every 10 gallon after 40% or more water changes).

As you can see the fertilizer amounts are higher than in Non Excel tanks. Also now it is recommended to perform 50% weekly water changes. The reason for this is that over time the excess nutrients in the water will start to build up. As a result we need to use the weekly water change to "reset" the system and bring down the nutrient levels in the water. It also helps maintain the water quality in the tank. Once your tank is well established you can try doing water changes maybe once every two weeks. Also if you are dosing leaner than recommended (with no visible signs of nutrient deficiency in the plants) then you could even try doing water changes once every month. However make sure to atleast do them once a month if not more regularly.

1) Dosing ferts as recommended above
2) Occasional pruning to ensure good circulation in the tank
3) Gentle gravel vacuuming on occasion to get rid of excess detritus (never do a deep gravel vac)
4) Feed fish every day
5) Do a major (60-70%) water change after any major pruning/rearrangement which involves uprooting plants and moving the substrate around.

As you can see, we do not skip dosing ferts once a month as recommended with non excel tanks. This is because we are now doing weekly 50% water changes to keep the nutrient levels in check.
All the other things mentioned in the non Excel tank post regarding Fish, Substrate and Planting remains the same for Excel based tanks. That is pretty much it. So what are you waiting for? Get started on your aquascaping you planted tank fiend!  :mrgreen:

Acknowledgments: Most of this article is based on all the useful information I have gleaned from scouring through the forums at Tom Barr’s site, www.barrreport.com . He deserves credit for a lot of the content in this article. I’ve just put it all together in one place and added some more stuff to make this more accessible to the planted tank newbie. The original thread related to this technique can be found here : http://www.barrreport.com/estimative-index...o2-methods.html .

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22 comments on “Low-Tech Excel based Planted Aquariums: A Guide
  1. Jason says:

    What is the Equilibrium recommendation? 1/8th what? I assume you meant 1/8 teaspoon?
    1/8th teaspoon would only increase hardness by a fraction of 1 dH(and Ca and Mg concentration by less than 1 ppm) in 20 gals of water. That seems like far too little to be adding…

  2. Sudeep says:

    Hi Jason,
    I think part of it is also dependent on what your native water hardness and Ca/Mg levels are. If you have very soft water then you would need to compensate more. Since you are doing 50% WCs every week, that will help bring up hardness levels to the default in any case. These recommendations are a rough guide and worked well for me (and also was what I found to be recommended over at barrreport.com). Depending on whether your plants have specific needs regarding hardness/softness you might very well need to increase this amount.

    Regarding the amount to raise, what do you feel (or what have you read elsewhere) regarding the appropriate dosing for raising hardness?

    Thanks for stopping by and leaving a comment.

    • Jason says:

      You’re right, dependent on tap water conditions…I essentially have zero GH in my tap water.

      My goal is to get to 2-5 ppm Mg and 10-20 ppm Ca.

      Understanding the Mg and Ca concentrations are nearly impossible to measure practically, I used published reports about the water chemistry at the reservior where my tap originates from to estimate a baseline, then calculated the amount of Equilibrium required to get me somewhere in that range.

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  3. Sarah says:


    You photos are beautiful and your guides very helpful! Thanks!

    I was just wondering if you could list what species of plants (particularly the grass cover) you are growing and how much wattage per gallon you are at? Cheers!

    • Sudeep says:

      Hey Sarah,

      Thanks a lot for the compliments. Since I was using fluorescent Spiral bulbs which are not very efficent at lighting tanks, I was using 3 WPG (2x15W 6500K GE Spiral bulbs)when I was supplementing the tank with Excel as a carbon source. Later on I backed off from dosing Excel (made it a total low-tech tank with once a week fert dosing) and switched the lights to 2x10W spiral bulbs at 2 WPG. Again, keep in mind that if one were using T5 tubes one would need to use much lower WPG since they are far more efficient at lighting tanks.

      As for the plants, the driftwood has Philippine Java Fern (I would strongly recommend this variant. I bought it off ebay from a seller called Aquaticmagic) with Anubias Coffeefolia (deep ridged texture and dark green color) along with a few anubias nana petite. The foreground carpet plant is dwarf hairgrass. It is a bit tricky to grow out and maintain and actually requires Excel supplementation in the very least to do well in a tank. The plants in the background are predominantly rotala rotundifolia.

      I strongly recommend these plants for a low-tech tank (except maybe the hairgrass which can be a lot of work and hard to grow out).

  4. Robin says:

    Hi Sudeep,

    I’ve read two of your guides (both on low tech) and I really appreciate you doing this for the lot of us out there, the guides are really helpful I have to say!

    Though I’ve one question, the local fish shops around my vicinity, sells a lot of plants, they are all bound together by a piece of wool and further tighten by metal pieces. When I actually want to plant in into my aquarium, should I take those off or leave them be?

    I thank you in advance and I look forward to your reply :)

    • Sudeep says:

      Hi Robin,

      I’m glad you’ve found the guides useful :) . You should definitely take off the metal strip that is used in shops. It can hurt the roots and it is generally a bad idea to plant with them attached. As for the piece of wood, it depends on whether the roots have actually anchored themselves within the wood (sometimes sellers sell anubias and java ferns that are growing on small pieces of driftwood) or whether the wood is just there with the roots tied to it. If it is the former, you can leave it as is (if you are okay with the wood in your tank) as the roots are already well settled and established within the wood. If the latter, I’d definitely get rid of the wood.

      When you plant, make sure that the roots are under the gravel so that the plant is anchored. Just make sure that for plants like anubias and java fern, that you don’t bury the rhizome under the substrate as it will kill the plant. For those types of plants, you can try to use an anchor to keep them down initially while they take root within the substrate.

      Good luck!

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  5. D. Martin says:

    Nice article. Im going to attempt my own 10 gallon low tech tank. Plants I will use are java fern, dwarf hairgrass, C. Wendtii, Wisteria (temporary), And rotala indica. I was thinking about starting with the excel method to kick start things, but wanted to know how long should you do this? Maybe a month or 2 before you cut back on lights and excel?

  6. Alex says:

    What substrate were you using for the picture above? It looks like black sand, and i really like sand, please email me back the response as I probably will forget to check here >.<

  7. Faizal says:

    Hi Sudeep. 2 questions please :

    1. Does the Excel affect shrimps & small crustaceans?
    2. Some people dose excel as per the manufacturer’s recommendation but they don’t actually do the water changes weekly. They dose the nutrients once a week for 3 weeks ( like a non co2 tank) then do a large water change at the end of the month. Is this okay?

  8. Jimbo says:

    Hey Sudeep, I am redoing a 20 and am really intrigued with the idea, question is should I just use the old fashioned hood and use regular “plant bulbs” or go to an LED like the marineland single led setup. I like the look and the “moonlight” feature. How deep do you go with your substrate. I am planning on using fluorite, but it is a little pricey. I’d like to have a school of tetras, some drift wood and plants similar to your photos. What is your advice?

    Thanks much!

  9. Brandon says:

    Hey there I looked up seachem flourish that you stated above in the dosages and all different ones come up like seachem flourish iron..nitrogen..phosphorus..trace..potassium and they all have different pictures on them. Which one do I use or do I use all of them thanks

  10. Jefc1 says:

    The number of additives seems excessive, followed by a very large water change.

    Doesnt make sense.

    1/8 teaspoon of KNO3, 1-2x a week
    1/16 teaspoon of KH2PO4, 1-2x a week
    2mls of Seachem Flourish, 2x a week
    SeaChem Equilibrium 1/8th once a week (Immediately after weekly water change)
    50% weekly water change
    Dose 1-1.5x the recommended dose for Excel (1 ml for every 10 gallons on a daily basis and 5ml for every 10 gallon after 40% or more water changes).

  11. Riyaz says:

    Hi Sudeep,

    First of all amazing information. Now I would like to ask for suggestion on setting up my first Planted tank.
    27 Gallon with 2-2.5 WPG(LED LIGHTS)

    1. Substrate – Aquaclay Gravel or DIY Substrate any other(less option of ready made plant substrate in my place only aquaclay is availabe).
    2. CO2 – Preferring to go with DIY Co2 can also go with Seachem Flourish Excel.
    3. I want to grow Dwarf Hairgrass and/or Marsilea Hisuta as my carpet plants.
    4. And other good looking plants too so that i can have a moderately planted aquarium

    Please guide me

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  13. How does the toxicity affect fish? I assume at a regular dose it should be dilute enough to not be a problem?

  14. Perry says:

    Where do you purchase your KNO3 and KH2PO4?

  15. Hi to all, the contents present at this website are genuinely awesome for people experience,
    well, keep up the good work fellows.

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10 Pings/Trackbacks for "Low-Tech Excel based Planted Aquariums: A Guide"
  1. [...] sense) which recommends 50% water changes. I believe this is just a summary of your work, Tom: http://www.sudeepmandal.com/hobbies/…-planted-tank/ I can't change that much water. The labour's the same (I just use a hose). We have crazy water [...]

  2. [...] out this guide out, it's based on Barr's suggestions, really helped me out with an excel tank: http://www.sudeepmandal.com/hobbies/…-planted-tank/ Finally, weekly excel is doing absolutely nothing. Its duration of effect is less than 12hrs. You [...]

  3. [...] This is basically what I will be shooting for with my 29 gallon tank, which I would call medium lit. Its 18" tall tank with a dual T5NO about 1-2" above the tank. If I were starting this tank from scratch I would first not be using the T5NO and I would be setting up the tank as low light/low tech using the method you first mentioned. __________________ The Fraternity of Dirt # 3 56K warning for these Walstad Bowls 29 Gallon SA Fish Low Tech 40 Gallon Asian/Pacific Realm Low Tech [...]

  4. [...] Gh7, 3Kh, 7,5 Ph. 11Gh, 2 Kh, 7.4 Ph when treated with equilibrium. I have a strange tap water… http://www.sudeepmandal.com/hobbies/…-planted-tank/ Attached Thumbnails [...]

  5. [...] some speedier growth in the tank, I'm going to try a low-tech Excel-based tank as outlined here: http://www.sudeepmandal.com/hobbies/…-planted-tank/ Following that dosing regiment, I'm going to try and use the lighting that came with the 20g tank [...]

  6. [...] 100 Heater: Fluval 50w Substrate: Seachem Flourite Ferts: Dosing regiment can be seen here – http://www.sudeepmandal.com/hobbies/…-planted-tank/ So, I'm going for a clean, low, open look. Here's what I'm thinking right now for the scape… [...]

  7. [...] Read this link, summary of method designed by Barr. http://www.sudeepmandal.com/hobbies/…-planted-tank/ [...]

  8. [...] ago. I may have recalled it wrong. Either way, I just found this guide and it answers all + more. Low-Tech Excel based Planted tanks: A Guide __________________ Success is measured by your ability to achieve a certain [...]

  9. [...] article Low Tech Excel based planted Aquarium is a good starting point on using excel. It does a great job summarizing Tom Barr’s EI dosing [...]

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