Hydroponics with Aquatic Plants

Jessy2363

Junior Poster
Aug 27, 2015
21
3
3
New Zealand
Hi


I've just recently got a greenhouse running to grow aquarium plants emersed. I'm using inert medias: Rock wool, Hydroton, Vermiculite and Perlite mixed and a couple others I'm trialling also. Anyway.. They do not contain any nutrients so no relying on nutrient rich substrate. The roots get oxygen every 15 min and nutrient water every 15 minutes. Flood and drain some call it. Nothing ever dries out and I have no issues with fungi thus far. No fish are involved in this operation so not aquaponics. I am trying to make this environment as controlled as possible. Humidity is around 75 percent most of the time and artificial lights are used.


So I got some ferts from a hydroponics shop and the plants hated them, they were supposedly made for aquatic plants. I tested the water according to their lowest dose on the instructions which happen to be an EC of 1 which is 500 TDS. Now phosphate was off the charts, nitrate was off the charts, Iron was all good but was around .06mg/L so still pretty high but not too bad. GH was around 20 something and my tap water GH is 2 so obviously it had GH boosters in there something chronic. I don't own a potassium test kit yet so can't comment on that. My Ph is around 6.5 but I lower it to 6 as I thought just maybe nutrient uptake might be higher as it is for most terrestrial grown leafy plants like lettuce. Anyway PH is not my problem the ferts are.


Cutting to the chase: I have decided to use my aquarium Fert methods on my hydroponics set up and ditch the shop ones. EI dosing of course. It's only a few days into my new EI hydroponic Fert regime so I cannot comment but I am pretty sure they are looking happier already. Bare in mind I am being a little more heavy handed with the ferts than I would in my aquarium. But Is this going to be enough nutrients considering the substrate is completely void of any nutrients whatsoever and the leaves are not submersed? Do aquarium plants grown hydroponically require the same or more nutrients than if they were grown in a High Light Co2 injected aquarium? Has anyone ever noticed that lettuce's and herbs etc require WAY more ferts than aquatic plants and why??? A generous EI dosing on my hydroponic aquatic plants and my EC is 0.3 (150 TDS) not 500 TDS like I originally dosed with the shop ferts (which are levels fit for herbs btw). Anyone know why aquarium plants require SO much less nutrients than lettuce's and many other terrestrial grown plants? Or is this not the case? Can I burn them with too much fertiliser? So many questions and google ain't giving me answers. I'd love to email Tropica but I very much doubt they would reply. There is a lot of info on how to grow vegetables hydroponically but not aquarium plants.


If anyone grows aquatic plants via a method of hydroponics whether it be flood and drain, deep water culture, drip feed, nutrient flow technique... the list goes on... I am very keen to hear from you and find out what your nutrient levels are in comparison to your Co2 injected aquarium (if different).


Regards


Jess
 
Last edited by a moderator:

PEdwards

Junior Poster
Feb 1, 2017
46
24
8
Florida Aquatic Nursery puts what looks to be a couple of Osmocote balls in each of their rockwool/potted units. If your plants are in a container that will allow water to flow/diffuse though it, it seems worth giving a try as long as the container part gets access to water.


If that's not possible, the next best thing would be a nutrient flow with the lower portion of the stem/root ball get decent flow. Just make sure the sump is well oxygenated.


Fill/drain may not work as well with vermiculite, but it should be fine with pumice, hydroton, and rockwool. This is the method I would use with rosette plants like swords and crypts. Stems and epiphytes/rheophytes will likely respond to nutrient flow better.


Could you post some pictures of your grow beds/containers?


As far as fertilizers go, I came up with a hydroponics line for a former employer and would recommend starting with the equivalent of 1/2 EI dosing or 1/4 dose of Miracle Gro 4-4-4 and ramping up from there as you feel the need. Emergent grown aquatic/wetland plants are really good at scavenging nutrients.


Cheers,


Phil
 

Jessy2363

Junior Poster
Aug 27, 2015
21
3
3
New Zealand
Hi, Phil


Thanks for your reply


So possibly I am overdosing on fertilisers as I'm dosing way above my normal EI as for some reason I figured emersed plants could handle more than being submersed as there's no algae to worry about other than on the media. Maybe i'm completely wrong there. I'll lower my dosing and see what happens.


It's such early days it's really difficult to tell if I'm doing a good job or not. The only plant that seems to be thriving so far is the lysimachia which we all know grows like a weed anyway so I"m not feeling proud yet.


Also the rock wool is getting quite a lot of algae on it as possibly it is too drenched on the surface with too much light. I am trying to grow glossostigma in it. It is not growing anywhere near as fast as I have grown it submersed so I'm doing something wrong there.


With the vermiculite/perlite blend I found the stem plants seems to do better in it then the hydroton because it remains wet longer and can "wick" the nutrient water up so the stem plant cuttings sort of rest sideways on there when first planted and sort of carpet along the media first then send shoots upwards once roots are established from the stem resting on top of the media. (hard to explain).. I need to make sure that the vermiculite and perlite 50/50 blend is well above the water line because I will risk getting algae on it if it's too low and soggy. The hydroton however I need to make sure gets a lot of water as it doesn't seem to retain moisture well and has no wicking property therefore it dries a lot quicker but less risk of algae. I am mostly putting swords in the hydroton because they have such big root systems they don't need to rely on the dampness of the vermiculite/perlite blend.


I'll try the osmocote method you suggested also and see what happens there.


Also that's good to know about the aquatic/wetland plants scavenging nutrients. That explains why they need much less nutrients in the water than normal terrestrial plants.


Anyway check out the photos of my set up. I'm saving up for more flood and drain trays etc so i've only got two trays side by side and an aeroponics unit running at the moment.
 
  • Like
Reactions: 2 people

Jessy2363

Junior Poster
Aug 27, 2015
21
3
3
New Zealand
I should probably mention that I purchased the swords so I did not grow them from scratch hence their large healthy size. They were grown emersed so have settled in pretty well thus far.
 

PEdwards

Junior Poster
Feb 1, 2017
46
24
8
It looks like you're doing everything just fine. Rockwool does tend to get algae on it as a general rule. I wouldn't worry about it too much. If it helps, I've got a few pots of crypts with rockwool (standard FAN stuff) sitting in about 1/2 inch of water in a 10 gallon tank with no circulation. After the initial melt they're growing back strongly but the rockwool is covered with algae. I only recently (about two months after setup) added a small fert tab specifically for planted tanks to the water to get a little extra nutrition in there.


As far as the glosso, it may do better in the perlite/vermiculite mix than the rockwool. May be worth giving a try.


If you're going to cut back on your fertilization, keep an eye on the plants to make sure they're not getting deficient in Ca, Mg, and K. You may need to supplement that more often than N and P.


Good luck! Keep us updated please.
 

Jessy2363

Junior Poster
Aug 27, 2015
21
3
3
New Zealand
Thanks for the info regarding rock wool, I decided to change the rock wool for sphagnum moss earlier today before reading this. I can get sphagnum moss a little easier also as it's available at my local hardware store and rock wool is not as I had to get that from a hydroponics supplier. The reason for the change is my PH was rising too high. So I read that rock wool does bring the PH up and you need to prepare it in a PH down and water solution before using. Silly me never did bother to prepare it so my PH was rising daily to around 7.6 and I was having to bring it back down with nitric acid every day and my nitrogen levels were climbing due to this. Also out of sheer laziness I don't think I want to prepare it ever. I did read a few times recently that if the PH is too high it blocks nutrients from being absorbed so the plants start to become nutrient deprived even though there are plenty of nutrients available. They call it a "nute block" on the stoner forums. Anyway I know sphagnum lowers PH and also it's a little fluffier than rock wool so perhaps it will hold a little less water and let more oxygen into the root zone also. It can still wick very well and I'm pretty confident I'll get good results although I'll let you know. I know it has the ability to store nutrients also as in a high CEC rating.


I am dosing the water with N, P, K, Mg, Ca, iron and trace so hopefully my ratios are all good.


I'll let you know how I get on with the PH as it is still climbing even without the rock wool. No carbonates or bicarbonates are being used in the system so it doesn't' make sense to me and i've been googling all day what the problem could be. I wonder if the perlite/vermiculite and hydroton has any ph rising properties within their composition. Some say yes and others say no not possible.
 

Renan Ogiwara

Member
Nov 2, 2020
40
3
8
31
Brazil
Thanks for the info regarding rock wool, I decided to change the rock wool for sphagnum moss earlier today before reading this. I can get sphagnum moss a little easier also as it's available at my local hardware store and rock wool is not as I had to get that from a hydroponics supplier. The reason for the change is my PH was rising too high. So I read that rock wool does bring the PH up and you need to prepare it in a PH down and water solution before using. Silly me never did bother to prepare it so my PH was rising daily to around 7.6 and I was having to bring it back down with nitric acid every day and my nitrogen levels were climbing due to this. Also out of sheer laziness I don't think I want to prepare it ever. I did read a few times recently that if the PH is too high it blocks nutrients from being absorbed so the plants start to become nutrient deprived even though there are plenty of nutrients available. They call it a "nute block" on the stoner forums. Anyway I know sphagnum lowers PH and also it's a little fluffier than rock wool so perhaps it will hold a little less water and let more oxygen into the root zone also. It can still wick very well and I'm pretty confident I'll get good results although I'll let you know. I know it has the ability to store nutrients also as in a high CEC rating.


I am dosing the water with N, P, K, Mg, Ca, iron and trace so hopefully my ratios are all good.


I'll let you know how I get on with the PH as it is still climbing even without the rock wool. No carbonates or bicarbonates are being used in the system so it doesn't' make sense to me and i've been googling all day what the problem could be. I wonder if the perlite/vermiculite and hydroton has any ph rising properties within their composition. Some say yes and others say no not possible.
Hello… are you running your business yeat?