Water parameters for good Macro Growth

[chris melb]

I think ive done a bit of reading re: good macro growth. Just wanting to summarise, share what i have read, learnt, in the hope that people can know what is needed to keep their macros alive.

From my understanding, and just wanting to clarify, Macros require for growth:
* NO3 (>1ppm)
* PO4 (>?)
* Fe (>?)
* Ca (400mg)
* Mg (that of NSW)
* Alk (dkh 8 to 10 - that of NSW)
* Ph (~8.2)
* Lighting around 6,500K
* Water flow
* Salinity (that of NSW)

Is there anything else i am missing? I have a tank with cheato, with NO3 = 20ppm, PO4 = 2ppm, (i dose iron weekly- yet to purchase test kit), calc is at 400mg, Mg, Alk and Ph are all at NSW levels, i run a PC 6,500k bulb over my fuge, yet my cheato does not seem to be growing, it seems to be slowly disintergrating. What are some possible reasons? Could it be that my PO4 is to high, ive read in previous post that plants and macros show a negative response to PO4 above .02ppm? (My test kits are all salifert)

 

[graveyardworm]

NO3 can be alot a lower, as long as its available, 2ppm PO4 is really really high. less than 1 ppm would be fine. If you have corals in the same tank/system then you would want less than .25ppm. Same as NO3, as long as its available. The PO4 in my system is not detectable yet I still get good macro growth. By feeding the animals in the tank everyday I introduce an adequate amount of PO4 for the plants. Although recently I did have a sporulation event of one of my caulerpa's, and havent quite determined the cause.

 

[chris melb]

Thanks David, is there any reason though that my cheato is not growing and is disintergrating? i cant work out why, i have no other competing macros either. I had read your post, about sporulation, i think the temp may have had an impact, i lost my calupera to temp i believe it didnt actually sporulate though (i left the lights on 24/7 when i noticed it went whtie) it just sort of melted.

 

[graveyardworm]

Personally i think your iron dosing may be on the low side at once a week. How much water do you have, what brand of iron, and how much iron gets dosed? At the very least I would spread the iron dosing out a bit over the entire week so the level is more constant, and its always available. Rather than alot at once then limited for most of the week.

Iron doesnt stay in the water column very long even without anything using it.

 

[chris melb]

interesting i see, ok i was actually thinking of getting a test kit, to test for iron, cause i dose iron using Azoos plant nutrients: -AZOO MARINE PLANT NUTRIENTS contains trace elements such as: P, K, Fe, Mn, Cu, Zn, Co and Mo. The other alternative is to use Kents Iron, i have finally found it here in Australia as of last week, but apart from that is there anything else im missing, thankyou for all your help, i will try dosing iron more regularly and see what happens.

 

[graveyardworm]

I am not familiar with Azoo Marine Plant Nutrients. Depending on what else may be in the tank I would be a little concerne with some of the heavy metals found in it, depending upon concentration. Cu, Mn, Zn, Co, and Mo particularly. Not to mention with so many elements being added at once it will be hard to regulate individual nutrients. I would go with the Kents iron for iron supplementing.

 

[PatriksS]

Re: Water parameters for good Macro Growth

<a href=showthread.php?s=&postid=9481134#post9481134 target=_blank>Originally posted</a> by chris melb
Could it be that my PO4 is to high, ive read in previous post that plants and macros show a negative response to PO4 above .02ppm? (My test kits are all salifert)

I have no scientific proof of this, but I've seen really stunted growth in almost all macroalgae when I experimented all too wildly with PO4 (around 2 ppm or more). Some of them just melted away, but slowly came back after some waterchanges.

It has been shown that excess phospate (more then slightly measurable) is very bad for calcification in corals, so maybe the same thing goes for some of the macroalgae, especially such "hard"/calcareous species like chaeto? Just a speculation though.

 

[graveyardworm]

I hear what you're saying about PO4 effecting calcification, but I dont believe cheato falls into that category.

 

[PatriksS]

Allright, then maybe its some kind of "gatekeeping"-issue the like it is said to be in freshwater? (plants waste resources on keeping the excess of some nutrient out) Just a theory.

It would be nice to know exactly why macroalgae dont like higher levels of inorganics in water column. Would probably need to ask Tom Barr on barrreport.

 

[chris melb]

Firstly a thankyou David, for mentioning the importance of dosing Fe (iron) daily. My macros have again started to grow. I have also changed from Azoo's plant nutrients to Kents Iron and noticed a difference the next day in growth, ive also tested iron levels and found it to be undectable, prior to adding Kents chelated iron.

I have also found however that the above tank specs with high PO4 (2ppm) the cheato does not appear to be growing as fast, and the one in the other tanks with high nitrates and lower PO4 (<1ppm) are growing really well. Im assuming the cheato does absorb calcium as it is calcerous, and PO4 may inhibit its growth, but at the same time too PO4 is considered (i believe) a necessary nutrient for growth of cheato. Interesting thought though about coral absorbtion of calcium and its relation to calcerous macros.