Too high in nutrients to grow Macros?

[chris melb]

Is it possible to have too high nutrients to grow macro, atm i have a tank with Nitrate of 100ppm, and phosphate would be around 2ppm my macro isnt growing much at all. calupera serrulata is what i have. I dose iron daily and calc 400 and alk 3.46, ph 8.2 are all fine.

 

[fraggin]

lighting?

 

[chris melb]

sorry 6,500K spiral compact bulbs 14hrs on 10 off

 

[graveyardworm]

I think you need more light. The caulerpa should be taking over.

 

[chris melb]

So the excess nutrients wont be limiting its growth?

 

[Samala]

Well, how big is the tank? When we consider light we gotta consider how much water it has to travel through to get to the plants.

I'm not sure if excessive amounts of nutrients has an effect on macroalgae or not. Its a very good question.

Just for now, I would back off on dosing iron until you actually start to see growth again on the plants. Too much iron in your saltwater system may not be good for the plants and other inhabitants.

>Sarah

 

[chris melb]

2ft X 18 inch tall tank, ive added some side lighting, with a t5 fluroscent tube, i thought that the spiral compact would b enough from what i have read.

Just out curiosity then, what sort of avg growth should i see from my macro - so that i can work out for example if its operating effciently if that makes sense (i.e maybe there is something i can do to make it export more nutrients in a nutrient rich system, making it more efficient), ofcourse this dependant on a number of factors i.e light and nutrients. But given i have nitrates as high as 100ppm and phosphates @ 2ppm, dose iron, maintain calc > 400 and spiral compact 6,500k bulb over a 18tall tank what sort of growth should i expect to get?

Chris

 

[moosejac]

The problem I had when I overdosed NO3 was not the good algae but the bad. All my desirables grew like crazy, but I was unable to control slime algae and dino's.

 

[graveyardworm]

I've got 85 watts PC over my 18 inch high fuge. 65 watts wasnt enough for good growth. Those spirals might be okay over a shallow 8 inch deep fuge.

 

[Plantbrain]

I have this plant growing like a weed.

I'm not so sure you have growth issues for excess levels of NO3.
Certainly not from PO4.
NO3 is pretty low toxicity over a wide range for plants/algae.

The source of the NO3, now that concerns me. If you are not dosing KNO3, then it's coming from the tap(better) or from fish waste, something rotting(bad). That starts out as NH4/NH3 which is very toxic.

More light, I use about 4w/gal of PC lighting.
That seems to grow most anything and at a decent clip.

I've routinely dosed and maintained about 20-30ppm of NO3, however, good growth can be obtained with less and dosing 5ppm every 3 or 4 days seems to work well. It depends on the fish/critter loading.

I have no fish, crabs, snails etc in this tank. So I have a fairly isolated system to measure the effects of the uptake.

The system has been set up a long time so denitrification data is already there and relatively low. Plants generally increase denitrification in aquairums though.

Still, the tank will "eat" about 2ppm NO3 per day of KNO3. Most of this is in the form of plants rather than N2 gas.

So that's "a rate".

I suspect low Alk /Ca and light, but also, increase you aeration inside the tank, so that the micro bubbles make contact with the plants for most of the light cycle.

Aeration micro bubbles really help growth rates.
It's also easy to add.

I'd do perhaps a 70% water change, but first and foremost, what test kit method are you using? Is it calibrated against a known standard?

If not, do not assume that NO3 ppm reading is correct, same deal with the PO4.

Never change/manage a system based on a test kit reading that you have not double checked against a reference solution.
If you use test kits, use them right!

Most get really poor in the upper ranges and the lower extreme ranges, and those are often when folks have issues, or think they have issues.

So do the big water change, dose thereafter, calibrate your test kits by making a stock solution(any dosing calculator will tell you how much to add to a DI water volume etc), increase/add lots of current/aeration blasting in the tank.

Pretty simple.

Regards,
Tom Barr

 

[kae]

<a href=showthread.php?s=&postid=10114737#post10114737 target=_blank>Originally posted</a> by Plantbrain
increase you aeration inside the tank, so that the micro bubbles make contact with the plants for most of the light cycle.

Aeration micro bubbles really help growth rates.

Regards,
Tom Barr

How can aeration or micro bubble help growth rates and what is the best way to aerate the water?

Thank you.

 

[Plantbrain]

Well, what/how do you think they might facilitate more growth under intensive growing conditions?

More gas exchange. Gas phase diffuses much faster, and the micro bubbles also break up boundary layers around blades/leaves etc.

You can run high current and not get the same affect however, so bound layers is not the whole story and likely a small part only.

The gas phase is 10,000X faster than dissolved forms at entery.

Since the CO2 in the air bubble is at equilibrium with the air above, the CO2 can be absorbed.

You can do this to some extent with Fw plants, but it does not work as well due the micro bubble size differences. Many plants grow below water falls etc.

Waves crash and form micro bubbles in the places where many species grow.

The bubbles also are sticky and can stick to noxious algae species and remove them.

See Fick's 1st law of diffusion for more on the theory part.
The constant is much lower for liquids for diffusion than a gas.

Regards,
Tom Barr

 

[chris melb]

Thanks all, some great info here, my test kits are Salifert and Sera i used both as colour charts on the Salifert arent all that easy to read, i havent calibrated them yet have problems obtaining KNO3 here in Aust, i would suspect that my nitrates are high and yes its from fish waste im feeding heavily in order to get my clowns to breed. Im due for a large water change.

I will do a large water change,
add more light
add mirco bubbles

and see what happens, interesting info on the micro bubbles thanks Tom.

 

[chris melb]

Thanks all, some great info here, my test kits are Salifert and Sera i used both as colour charts on the Salifert arent all that easy to read, i havent calibrated them yet have problems obtaining KNO3 here in Aust, i would suspect that my nitrates are high and yes its from fish waste im feeding heavily in order to get my clowns to breed. Im due for a large water change.

I will do a large water change,
add more light
add mirco bubbles

and see what happens, interesting info on the micro bubbles thanks Tom.

 

[Plantbrain]

I'll say also that in general FW plants tend to be more adaptable and responsive to higher CO2 levels than marine plants.

Many macro algae and micro algae respond well to a 5% CO2 enrichment in small culture.


In tanks, it's another question and how the CO2 impacts corals is a debate that's yet to take place.

My guess, based on the CaCO3 forming macro algae, it's not really a large issue, the hard CaCO3 formers light have issues still.

It's hard to generalize without trying many species of both macros/seagrasses as well as coral and CaCO3 formers and seeing.

Snails tend to get their shells eaten up in FW system even with good KH/GH with CO2.

FW shells also have a protective layer that's generally not prersetn in Marine snails also.

Lots of unanswered questions there.

So the other basic question: do we need CO2 and will the trade offs be worth while?

I really do not think so, however, I might be wrong.
I've tried it and did not see a significant increase.

Aeration did and has produced a high level of growth and horticulture for macro and seagrasses.

So can I improve upon things?
Yes.

CO2?
Lot of work still to be done there.

I can do a dry weight comparison at some point.

CO2 dissolved vs aeration micro bubbles
Then CO2 dissolved vs CO2 micro bubbles

Rather than dry weights, O2 levels are often used in situ as they offer a measure of growth rate production for comparisons of treatments.

Regards,
Tom Barr

 

[piercho]

I'm not sure if excessive amounts of nutrients has an effect on macroalgae or not. Its a very good question.

I don't know about direct effect but indirect effect of epiphytes can be huge. IME both Chaetomorpha and Acanthophora easily overwhelmed by epiphytes if tank not running lean. Filamented algae and microalgae grow great guns and the smothered macroalga barely survives until nutrient levels come down. Caulerpa, however, seems very resistant to epiphytes because it is so chemically nasty I assume. Sargassum also very resistant IME. Thats why I think people should not get myopic on one alga if growing plants for export. Grow a variety and export what produces best under current conditions. But Sargassum and Caulerpa need lots of light and gas exchange for high production rates which is the problem here, as already pointed out.

 

[Plantbrain]

Define "lean".

I have a rough time with folks suggesting things that have no hard data for support.

Either they winged it, or never bothered to test or perhaps forget to say at what specific point they had a noxious species of algae occur.

Cough the data up.
Growing plants is not merely a function of nutrients, it's CO2/gas exchange, loading, light intensity etc.

Not every issue is reduced to NO3 and PO4. Nor are their correlation = to causation. Many seem to believe correlation = causation.
That's a very dangerous slippery slope when you go there.

NH4 and internally cycling, many other things need ruled out.
Most reef waste starts not as NO3(say from KNO3), rather, NH4.

I also grow many other species of macro algae, add good levels of NO3(5-10ppm) and smaller amounts of PO4(less than 0.4ppm), I do not have epiphyte issues.

Regards,
Tom Barr

 

[Samala]

Alright, in the interest of "coughing up the data"....

I have trouble keeping epiphytes down when the tank runs from 0-0.5 NO3 and O PO4 and when it runs 30-50ppm NO3 and 0.8 PO4. I've not gone higher with the PO4 actually. The troublesome algae at the high levels is diatoms, green glass algae, and little wiry reds that crop up from live rock. The low range often produces cyanobacteria when the tanks are less than a year old. In older tanks it tends to be more diatoms/maybe dinoflagellates and probably cyano, but not enough to really notice.

So, I like to keep the tank around 2-5ppm NO3 and 0.1-0.2 ppm PO4 or so. I sometimes keep it around 10ppm NO3 just for yucks. No real differences in growth or nuisance algaes then.

>Sarah

 

[piercho]

Tom,
starting point for "lean" for me is NO3 not detectable with test kit that is suppose to indicate down to 0.1 PPM. Past that its just a subjective guess based on what kind of rates of production I see in tank. I get no indication with a NO3 test kit unless I add KNO3. I don't have a comparison kit so I have no idea if the kit I'm using is even in the ballpark.

Acanthophora usually grow clean of epiphytes for me. Lately I tried adding KN03 that should have bumped my tank NO3 level up to 2 PPM. I only see about 1/2 that level of NO3 with a kit right after dosing and none detectable the next morning. I try this a couple of times and one apparent result was the Acanthophora production stopped and a lot of green hair-type algae show up in the filter tank and microalgae on the Acanthophora. I got no hair algae in the display tank but the light level is lower in there and it has large grazers. The tank seem to soak up KN03 fast, but it did not increase growth rate of Acanthophora.

I can guess what you are going to say, I need to use more KNO3 more often. At this point I'm not trying that but maybe eventually.

 

[Plantbrain]

I have the same type of results, fairly close, as Sarah's there.

I really doubt your test kit have even remotely the accuracy and precision to measure NO3 that low. Most at best are like the Lamottes at 1 ppm maybe 2ppm etc. There are ULR test kits that measure well, but these are generally colorimeters/spects and certainly need a calibration curve and ref standards done.

Same deal with low PO4.

All the test kit methods unless specifically addressed, test total PO4 or total NO3.

Not Inorganic forms.

eg SRP PO4 is the standard method for inorganic fractions of bioavailable forms.

We might measure 0.1ppm PO4 but it's not bioavailable to the macros, pest algae might be able to cleave the bond however and use it, or the low trace ppb ranges that leach out of coral, rock, sediment, macro algae are more than enough to support growth and non limiting conditions for many species.

I really have issues when we get this low and start thinking we have such precision at such extremely low concentrations, that's very tough to measure and show in a research, let alone in a hobby.

There is not even a private lab that the SFWMD could send samples to the would guarantee 10ppb of PO4 +/- 3ppb for the indepenedent analysis in their monitoring program.

Chemostat experimenet suggest the sub 10ppb range is limiting to small noxious algae. They are a PITA to keep going also(Chemostats).

This is why looking at the upper end of the curve is so appealing and useful to hobbyists.
Far easier and from a how/management perspective, much easier and addresses good growth for far more species.

I've grown 48 species of macro algae and marine plants well.

The 2ppm of NO3 might have been removed by bacteria in a DBS.
But I think the macros got it.

The macro algae might be limited by Fe/PO4 etc, so adding more NO3 really did not do much, however, another species might have been limited by something, it might not be NO3 either.

The NO3 was low, you added some, so generally speaking, if you add one thing and not the others, the PO4 might have dropped to zero, of the FE.

Plants, macro algae all self regulate their metabolisms, so if you add say PO4, that will increase NO3 uptake by the plant. Likewise if the plant is limited by NO3, adding more PO4 will not do anything either.

Secondary effects are very common in plant phyisology and in reefs/FW planted tanks/ Agriculture etc.

They do not imply cause however.

You have to have control over the all the parameter to test the one of interest and they need to be non limiting over the duration of the test.

Then you vary the compound of interest over a wide range and and see the results.

If you had a limited NO3 system and added PO4, would you expect to see a high O2 production rate from the macro algae?

I wouldn't.

Regards,
Tom Barr