View Full Version : Plant Suggestions for Low Light with CO2 & Ferts?

08-04-2010, 08:09 PM
I have a 20 gallon tall waiting to be setup that I want to plant. I'm fairly new to planted aquariums, so I'm looking for some suggestions and any advice anyone might have. I have basically everything ready, except a "plant plan". The tank has two 15 watt 6500K compact fluorescent bulbs Life-Glo I believe, so 1.4 Watts/G, and about 25 pounds of white aqaurium gravel, so about 1.5-2 inches deep. I will be using DIY CO2, Flourish Comp, Potassium, Iron, Flourish root tabs and equilibrium to raise gh. The fish I will be putting in are 1 clown pleco, around 8 show guppies, and once established 3 or so otos. I also have two pieces of driftwood and a small rock cave. The important water parameters in my current tank with driftwood and CO2 are as follows and I figure this new tank will be similar;
KH 2.5
GH 2, will be raised by equilibrium
Nitrate 5
PH stablized at 6.4
Temp 72-80 depending on the season

Current plant stock:
Clippings from Cabomba
Clippings from Magenta Rotala

I have heard many people say that under low light with CO2 and nutrients, you can grow almost anything, however I think the lower PH may limit my choices if I am correct? So any suggestions of plants that will live in a lower PH? Keep in mind I have a stock hood, so any plants going in front will get much less light and I do not want to have to trim plants back every three days, so anything like duckweed and the sort is out of the question. I'm also not too fond of mosses as I like to see my substrate. :D

I also have a few questions..
I recall someone saying that you cannot dose certain ferts on the same day or they will bind? Which are these? Should I only dose trace + micro after water change? Potassium once or twice a week? And how often for iron, some say everyday?

Sorry for all the questions, but I just want to get everything straight beforehand, so I don't waste hundreds of dollars. :D

Thanks a bunch!

08-04-2010, 08:43 PM
Welcome to the forum Distants. Sounds to me like you have a good base started for your plants.

There are a few thingst that you should consider about your current plans. Firstly, is your lighting, which is very low for the two plants you have 'planned'. Cabomba is an extremely hard plant to grow, even with nutrients & high light (over 4 wpg). Some with high light have great luck with it, but you will not with the lighting you have. The leaves tend to break off and clog filters if the conditions are not exact. The Rotala might be able to stay alive, but it will be very pale green and likely won't show any signs of the nice magenta colour you are likely going for. If you are wanting to grow rotalla in your 20 gallon, i would reccomend looking for at least 60 watts of CFL.

With your lighting, I would stick to plants like anibus, ferns, cypts, moss balls, and java moss. With the plants listed above, you likely wouln't need that much fertilizer as these plants grow fairly slow. You could likely does 2wice a week, even with CO2. Without CO2, it would be likely that your fish would produce enought waste, that in turn would fertilize these plants.

About PH - most plants prefer the lower PH, and will be very happy in your tank.

As for your questions:
Dosing certain ferts on the same day - i believe with the ferts you are using you will be fine. The issue comes from doseing "dry ferys", which you are not doin. There are two compounds that don't match, but I can't remember what they are.
I would stick to dosing one or twice a week for your plants, and go from there. If algea shows up, cut it back. One thing I would reccomend is keeping your CO2 constant, and changing your fert schedual to fit your plant/algae needs.

If you really wan't to get into plants, I would reccomend increasing your light.

08-04-2010, 09:17 PM
Check this site for a list of plants with your lighting:


Plant Man
08-04-2010, 11:23 PM
Check this site for a list of plants with your lighting:


If your going to run DIY Co2 run at least 2 bottles and chnage one every week or every two weeks.

1 cup sugar, 1/4 teaspoon yeast, 1/8 teaspoon baking soda in 2 liters of tank water.

Your light is good. I have grown Java Fern/Moss, Anubias Nana, Amazon Sword, Ludwigia Glandulosa, Lobelia Cardinals, Hemianthus micranthemoides (baby tears), Cryptocoryne Wendtii "Brown and Green" under 1.4 watts of T-5.

Use 1 cap Flourish Excel with your DIY Co2 and do weekly large (40-50%)water changes. Sounds like you have very soft water. I would dose dry if you can get it. Look into dosing half IE.

08-05-2010, 02:34 AM
Thanks for the info. I may look into increasing the lighting in the future, but I'm not really willing to buy a new light fixture just yet, since I will be moving sometime within the next 3-4 months. If I could only find decent 20-25 watt CFL's that would fit into my incadescent fixture it would solve my whole problem. I've tried several hardware stores though, ended up paying $40 for 1.5 watts, ugh. The rotala and cabomba are growing in my 10 gallon. I picked them up about 2 months ago, knowing nothing except they looked nice. Cabomba seems to be iffy with a lot of people, but it's growing nicely in my 10 gallon under a 15 watt bulb, a few leaves lost on the bottom but seems fairly happy now. The rotala has stopped growing upward and the top leaves are very small, i'm assuming from very little nutrients, but there are shoots off almost every node of some of the stems. They've only been given a few drops of flourish comp after the weekly 30% water change. The potassium, iron and equil arrived today, bought online for half the price of my LFS. :D

08-05-2010, 03:51 AM
If you are going to pass on the light upgrade you may want to reconsider the CO2 - this is going to impact your pH and low light plants won't need the CO2 - they grow slowly so you don't want to add ferts or CO2 the way you would for high light plants. I have kept high light and low light planted tanks and have found the key to success is matching the additives to the plant growth. Otherwise there is an algae out there waiting to take advantage of the unused nutrient! If it looks like your plants are not thriving and you suspect it's a CO2 problem add a little Flourish and see what happens. My money is on it not being a CO2 issue!

08-05-2010, 04:26 AM
I really enjoy the red plants though and thought they would contast well with the gravel, and I always find without CO2 I get mass algae problems, even with just java fern, no ferts, 8 hours of light.

If I were to bump my lights up to say two 20 watts, would it bring me more into a medium light category?

And if someone could tell me if these bulbs would be appropriate for a planted tank? I haven't heard anything about actinic blue phosphors..

08-05-2010, 06:29 AM
I would try and get the two 20watts for that. You'd have nice 40w, which follows the over said rule of 2watts per gallon( Which doesn't always apply.) and you could keep some really nice plants, though you'd sill have to look at getting T5HO fixtures to keep those two High light plants...

08-06-2010, 04:09 AM
I haven't had much luck finding and growing any deep red plants in low light. You can get some nice brownish reds in the crypt group, but those gorgeous reds, not so much. Frustrating for me because I don't want to do CO2 gas and expensive lights and ferts regime again - just don't have the time, energy and money this year! At 4 watts per gallon though you should be able to grow some nice looking reds - if it were my tank I would add the CO2 gas at that wattage and dose fertilizers in order to get the biggest bang for your lighting bucks.

08-06-2010, 04:17 AM
Okay, thanks. I have seen a few reds that supposedly grow well in mid light. On Monday I think I will go to the hardware store and see if I can find any 23-25 watt daylight or full spectrum screw in CFL's. That is the maximum wattage my current light fixture will hold. That way I should have 2.5 watts/gal which should be enough to support some decent plants, hopefully. :shappy:

Plant Man
08-06-2010, 02:50 PM
Okay, thanks. I have seen a few reds that supposedly grow well in mid light. On Monday I think I will go to the hardware store and see if I can find any 23-25 watt daylight or full spectrum screw in CFL's. That is the maximum wattage my current light fixture will hold. That way I should have 2.5 watts/gal which should be enough to support some decent plants, hopefully. :shappy:

You really don't need 2.5 watts per gallon. But it all really depends on how much light you’re getting from those bulbs. Wattage is not a good way to measure total light output. I would try with lower wattage first. Keep it in the 1-1.5watts range, if your not getting growth and everything else is there (Co2 30ppm, ferts) then up the light a bit.

High Co2 and lower light is the way to start. But you must make sure you have a good fertilizer regime. Make sure you’ve got Phosphate, Nitrate, and Potassium in the tank. Everything else you’ll get from your tap water or you can boost it with a Micro nutrient dose like Tropica or CSM+B.

Phosphate or Nitrate do not cause algae, to low Co2 ppm in conjunction with to much light does.

These plants are growing nicely under only 1.4 watts of T-5 for 11 hours per day. I even had then growing under .91 watts, my red plants started losing there color but they grew non the less. You can see down in the right corner Ludwigia stems turned green but they grew thick and healthy.


08-06-2010, 07:40 PM
Hmm, okay thanks. There seems to be a lot of controversy over what can be grown, or even kept alive under low light. I'm still thinking that I might up the wattage of light, somewhat at least to maybe two 20 watts. That way I can return these ridiculously overpriced bulbs and then start searching for some plants. I've started a list of plants that I like and believe would do alright under 2ish watts/G. I figure I should be able to find some of them, between the 3 pet store chains and the few smaller pet stores around here, but not all. Our only fish-store recently went out of business. Anyway, here's the list;

cryptocoryne wendtii
anubias, probably nana
micro sword
water sprite
dwarf hairgress
baby tears
java fern
cryptocoryne parva

Anything that I am wrong about, and totally wouldn't do alright in 2-2.3 W/G?

08-06-2010, 08:01 PM
I am not a super plant expert like some on here but I will give my input from my experiences.

I agree with not needing a light upgrade however, in my opinion the depth of your tank should be factored in to the equation too not just WPG since you mentioned that your tank is a 20G tall. I am growing pretty healthy plants although they are more considered to be low and medium light plants and probably no where near as well maintained as Plant Man's tanks. I go with 2x20W T8 bulbs on a 31G at a depth of 17.7 inches and 2X40W T8 bulbs on a 58G at a depth of 19.7 inches. This calculates out to be 1.29 and 1.38 WPG respectively. Not sure how high your tank is but the WPG 'guideline' might not hold true. Give it a try and see what you can grow before dropping the money on a light upgrade that you may or may not need.

Also agree that having Co2 available for the plants is more or equally important to having light. While the plants can survive without CO2 they wont grow as quickly or be as healthy with it and chances of algae increase. Likely you will start seeing nutrient deficiencies starting to appear and algae. I have a small 6 gallon tank that I have CO2 running into with absolutely no fertilization and the plants are looking really nice and have very little if any algae anywhere in the tank.

Even with CO2 I think another factor in determining fertilization schedule is how heavily planted is your tank? 3 or 4 plants will not require you to dose as much ferts for the tank size vs a tank that is crammed full of foliage. Find the balance that works for your particular tank so that algae doesnt become a problem.

As for red plants, I think the rule of thumb that I have heard is that the more dark or dark green the plants are, the less light they need. As you move into the reds you need more light as well as more iron as well as some of the other nutrients in order to bring out their true colors. With less light the 'red' plants will grow but be more green as they produce more chlorophyl to photosynthesize. Hopefully someone can confirm how good a guideline this is.

list of some of the plants I am growing or have tried:
anubias nana and barteri
cryptocorynes beketti, wendtii mi oya, wendtii tropica, undulata, and balansae
echinodorus bleherae
java fern and windelov
barclaya red
hydrocotyle verticillata
valisneria giant and corkscrew
hygrophylia difformis and polysperma
pogestomon helferi
marimo moss ball
aponogeton madagascariensis

08-06-2010, 09:58 PM
I too am in agreement with PlantMan (shocking, I know) on this. Too many people are too in love with light and end up throwing way too much light at their plants and not enough CO2 or ferts. The more light you throw at your plants, the higher the demand on CO2 and ferts will be. You would be absolutely amazed at what you can grow in "low" light with the right balance of CO2 and ferts. I would highly recommend you stick with the lights you have and learn to grow plants with those first, then if you want a high light tank try.

08-06-2010, 11:44 PM
My tank is 16 inches high. But, I bought these two 15 watt screw in CFL Life-Glo bulbs that are 6500K and "full spectrum" for 25 bucks a bulb, which I was told I could return if they don't work out. Now that I've done some research it appears that I could just use those spiral screw in CFL's that are 6500K daylight and maybe ten bucks for two. Or are the Life-Glo bulbs "special" in some way?

08-07-2010, 05:45 AM
ouch... I would say those are overpriced... you can most likely go find any CFL bulbs that are rated at 6500K at your local hardware store for much cheaper. I am right now using CFL that say 3000K on them on a small 15 gallon hospital/QT/plant nursery tank that is 12" high... seems to work just fine.

16 inches and your tank is considered high? must be more square shaped?

08-07-2010, 04:30 PM
Okay, thanks for confirming. They're way over price, the whole tank was nearly the price of these bulbs.

My tank is 16 H x 12 W x 24 L, but it is labeled 20 gallon tall. I suppose you can get nearly any measurement of tank now, though..