Why your Caulerpa metled

[Plantbrain]

I see this question every week.
So in answer to your queries:

Caulpera needs a fair amount of NO3 to grow at a given rate.
It also needs lots of Ca and CO3(alk) for support.

As most of you are aware, the growth rates of Caulpera are rapid.

If your tank has only a given fixed rate of NO3/NH4 production, once the Caulpera gets enough biomass, it will no longer have enough NO3/Ca/CO3 etc to support this biomass. It will then melt.

You can dose NO3 to solve this issue and top off with an inorganic source, KNO3 if you chose or............

You can prune regularly to maintain and relatively stable biomass of Caulpera.

People see their Caulpera growing like mad and they leave it alone. After a peroid of time has past, then all of a sudden it all dies off and goes sexual. Then they come here and go "why did this occur?"

Rather than figuring out why it occurs, they suggest another macro.

It has eaten itself out of house and home.
It thinks times are now "lean" and it cannot maintain it's old growth rate/maintenace.

This is similar to plants producing seeds to make it through dry peroids or winter etc.

You need to balance the bioload to the plant biomass and keep this ratio stable.

Adding Ca/Alk/Traces are only part of what they need to grow, they also need decent N levels.

Less N/P etc is not better.
Macro algae need more than smaller noxious algae species.

So give them what they need to grow well and they will never go sexual on you.

You can try this for yourself and see this pattern.

Regards,
Tom Barr

 

[mthedude]

would it be safe to assume that those w/refugiums full of macros and claim to have 0 nitrates and 0 phosphates are simply getting that reading because the algae is using them up too fast to detect on thier tests?

Excellent post by the way!

 

[Plantbrain]

Readings very low ranges of 0.0 ppm NO3 and 0.0 ppm of PO4 assume that your test kits are infaliable.

They are __garbage__ in most cases. We use known standards(these are easy to make and most aquarist can and do do this to re check their test kits over a range) to test and make test kits, calibrate water testing equipment.

You need the NO3, PO4 etc and DI/RO water and some form of measurement.

Some low ranging nutrients can be used up as fast as they are produced. That's fine if you have a decent balance of bioload/plant-macro load.
Otherwise you might be skirting the edge and allowing poor growth if any thing runs out.

Having a little buffer of NO3 will help.
I see little point in trying to limit both NO3 and PO4.
If something is limited, it will be limited by the lowest essential nutrient, not both at the same time, although it can occur(very rarely), it is of no use practially. Much reminerlaization and recycling of nutrients occurs on the surfaces, not in the water column.

People assume the noxious small algae are limited and that the other macros are somehow getting nutrients(magic?).

This is patently incorrect.

The other issue with test kit is that the resolution and accuracy really decline when you get at these low ranges.

Is there a good test kit that can tell between 1ppm and 0.5ppm of NO3?
0.1 and 0.2ppm of PO4?

We have trouble telling the difference between 0.01ppm of PO4.
10ppb is not much PO4 to test for. Resolutional errors are about +, - 7ppb at the top labs, this is still outside the range of limitation for many algae, eg, they have plenty of PO4.

Can these test kits tell you which form of NO3 and PO4 it's testing for? Bioavailable PO4 or total PO4?

Reef folks place way too much accuracy on test kits that are wrought with errors and assume they are correct.

They also tend like most aquarist to assume that correlation implies causation, it does not.

Build up of PO4 might be from poor Ca, traces etc which leads to poor macro growth(and thus less PO4 uptake) and that is the reason for algal blooms, not PO4 or NO3 etc.

There is a lot of finger pointing/ppoor test kits/assumptions but little apporoach in resolving the real players.

If you want to grow Coral, macro's ...whatever, give them what they need to grow well.

Regards,
Tom Barr

 

[kmk2307]

Tom,

I would like to start dosing a little nitrate to keep my macros happy. What do you think of this KNO3? http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=11812&item=3847834465&rd=1

Any estimates on what the dosage should be? I figure I'll add a known weight to a gallon of topoff water and see what the nitrate concentration is. How long until I have to worry about having elevated K in my water?

Kevin

 

[Plantbrain]

I use Grant's stump remover from Home Depot/OSH etc.
Cost about 5$lb

I actually use some KNO3 from an ar Turf place, it's about 22$ for 50lbs.

See www.gregwatson.com

For cheap iron trace mixes and KNO3.

Add roughly 5ppm 1-2x a week or so. Unless you have fierece growth, I dount that you'll more than this.

This will also force more PO4 limitation to occur by relieving the N limitation thereby increasing the PO4 uptake.

So if you buy into the notion of PO4 limited systems are better, then this would be a good thing.

I've dosed PO4 in my tanks, I kept getting diatom blooms.
I need to work on that one more.
CO2 also.

Regards,
Tom Barr