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

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 up to 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 Seachem 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 at least 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, . 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 : .

Rules for Distribution:

You are welcome to share the information in this article on other forums/websites subject to the following conditions:

1) The article must be unaltered and used as a whole
2) Do not claim credit for this work
3) Provide credit to me somewhere in the posting and a link back to this article on this site


48 thoughts on “Low-Tech Excel based Planted Aquariums: A Guide

  1. 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. 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 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.

    1. Sudeep,
      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.

    2. Hi sudeep,
      Instead of excel can I dose very small amount if co2 as I have a 4kg cylinder filled wit co2.may a bubble per 3 tank is 7 gallon should I need 5-6 wpg or shall I follow ur 2 wpg.I’m using 1 (14watt ) pll light.thank u for ur reply

    3. Hi sudeep,
      Instead of excel can I dose very small amount of co2 as I have a 4kg cylinder filled wit co2.may be 1 bubble per 3 tank is 7 gallon should I need 5-6 wpg or shall I follow ur 2 wpg.I’m using 1 (14watt ) pll light.thank u for ur reply

  3. Hi,

    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!

    1. 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. 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 🙂

    1. 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!

  5. 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. 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. 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. 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. 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. 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. 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. I’m using this Excel for plants that requires low to medium lighting. I’m new to this. Since I’m using Excel, do I have to get the other chemical ingredients such as Florish or equilibrium etc? Please help. Thank you

  14. Should I be dosing your required measurements of pottasium and phosphorus or should I be following what’s on the bottle, I am just confused with the huge difference in amount, 1/8 tsp is converted to .616 mL and the bottle is telling me to use more then tripple that amount. Please help

  15. I just wanted to express my gratitude for your articles. My story is far from unique, as a matter of fact it seems to be rather common. I started out with a 20 gallon tank with a few platies and a few black skirt tetras. I enjoyed my aquarium, however I never felt satisfied with any artificial plants that I could find. I was very reluctant to purchase any live plants, mostly due to all of the comments I read about the upkeep and serious maintenance involved. But last week I bought a few live plants to test my luck with them. I was disappointed in myself for not getting any sooner. There is no acceptable substitute for live plants. And now I’m about to setup my first 40 gallon acrylic tank, heavily planted, no CO2 , low tech excel method. I’ve found forums to be more confusing than enriching. When I found your works I was delighted. All of my questions were answered, so I’m less apprehensive now, and more excited about my future experience in the planted tank world. Thank you for your work and sharing your wealth of knowledge. Sincerely, Ross M.

  16. Can you please elaborate how did you reached 1/16-tsp of KH2PO4. IMO this would dose a lot of PO4, enough to cause problems…If you could please provide some explanation….Thanks.

  17. Your (or Tom Barr’s) website has been main guidance and helped me lot in setting up my 100 gallon planted aquarium! Thank You very much! Thanks to You I can own beautiful aquarium today, which I am really proud of 🙂

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  19. Dear sudip,

    My tank is a 42 gallon!
    I have hygrophilla difformis, bacopa monnieri, corymbosa, star grass, anubias barteri, sagittaria subulata in my tank! u told in the article there must be 10-15% visibility when looking from the top of aquarium! what else can i plant inorder to make it dense! i need to breed tetras in the planted tank itself! I have a wavemaker and a eheim pickup 2012 for filtration! i daily dose fert (EI stock solution) , Flourish and 10 ml excel! my substrate is DIY (vermicompost, 3mm quartz sand, blocks of laterite plunged in the vermicompost, 2mm gravel at the top)! My lighting is 3×20 watt of philips tube! suggest me anything so as to improve the rate of growth of carpet plants! what more stem plants can i include?
    any other suggestion of dosing,planting!
    Fishes include: white cloud mountain minnow,pristella tetra, cardinal tetra, chineese algae eater,glowlight tetra and 2 sail fin mollies!

    All i need is to breed tetra!

  20. I don’t understand the recommendation of 1/16 teaspoon of KH2PO4. Even EI recommends about 25% as much KH2PO4 as KNO3.

  21. Thank you for your articles on planted tanks. They explain Barr’s concepts better than Barr does himself. I have reprinted both in the newsletter of the Missouri Aquarium Society, The Darter. I expect our readers will enjoy them as much as I did.

    1. Hi Mark, thanks for your flattering comment! I’m glad that these articles are still proving useful and I hope members of your aquarium society find it useful. Apologies for the late reply, for some reason, I’ve stopped receiving notifications for new comments.

  22. That is a fabulous breakdown. I wonder if you have an equipment list for starting an aquarium up? I would love to know which filters, heaters, etc., work best (and if I need some sort of bubble system, etc.).

    Thank you so very much for this info. It is beyond helpful.

  23. This may seem like a silly question and thank you in advance for humoring me but why do the WPG go UP on a smaller tank? Say, for like a 5-gallon tank? Shouldn’t the light intensity be higher for a smaller tank with the same light? For example, If I have a T8, 15 watt, 6500K fluorescent light…wouldn’t that light intensity be weaker on a smaller tank?

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