rotifer disaster

Today on another thread Jim Welsh wrote:
       "Studies have shown that excessive density of adult copepods can have an adverse effect on nauplii production, e.g., "Management of nauplius production in the paracalanid, Bestiolina similis (Crustacea: Copepoda): Effects of stocking densities and culture dilution", VanderLugt and Lenz, 2008.  In short, assuming that you succeed in producing a large number of copepods in your culture, and a large number of them survive to adulthood, it is very likely that the increased density will result in a significant decrease in egg production, and possibly cause a sudden crash of the copepod culture, once the adult population dies off due to the limited natural lifespan.  In other words, if you are successful at culturing these copepods, it is important to regularly split, harvest, dilute or otherwise manage the adult density in order to sustain a relatively high nauplii production rate.  More on this to follow."
 
Does this follow for rotifers?  Could this be the reason that my newly split cultures aren't getting thicker.  I know I have live rotifers, I can see them under the scope.  But for the last 3 days the cultures aren't getting less green.  Even the one contaminated with brine shrimp.  I can't figure what I should do to get back on track. 
When I split them, they were going clear regularly and I had no fry in need of feeding.  Anticipating a hatch, I sieved  the cultures before I tossed the waste.  Now the cultures don't loose their green.  I have both RGComplete and live phyto.
What is the tried and proven method to create a new dense culture from a sick one.
How do I tell a)  if there are enough nauplii in the start sample  b)  how large a sample should I start with and c)  what ratio of starter to SW to RGComplete.
Because obviously I'm not getting it.

I don't think that this applies to rotifers at all.  I have always had the best success with rotifers when I have followed the instructions found on this site:  http://reedmariculture.co...otifers_culturing.html
 
As I understand it, the two main keys to successful rotifer culturing are:
 
1)  Feed well.  Never let them run out of food.
2)  Harvest 25-40% daily and religiously.  Without fail.
 
 

Don't feed too much, a light tint is all that is needed, but feed frequently.
Do harvest as Jim suggests, but harvest and replace that percentage of water as well as rotifers.
Rigid airline bubbling somewhere between a simmer and a rolling boil.  
In winter, I heat the rotifers as well.
A backup culture: no air, no heat, once a day food: This is where I put the harvested rots and their water, after I remove the same volume from this bucket daily.  It's a slower culture that is constantly refreshed.  If the main culture crashes, I've been able to recover with these ones that are not stimulated to reproduce as fast. 

check out Kathy's Clowns, llc website:
http://kathysclowns.com
Captive bred clownfish and more
(Wholesale to the trade.)

When you seived the culture and discarded the waste, did you replace the water with the same temperature and salinity water? If not, your rotifers may have been shocked, and will not replicate as fast.  Give them a little time, keep the water clean and lightly fed.  Gradually increase the feed as the water clears regularly.  I use a peristaltic pump on a timer to feed around the clock.

check out Kathy's Clowns, llc website:
http://kathysclowns.com
Captive bred clownfish and more
(Wholesale to the trade.)

 
How long do your backup rotifers last in that state?

Hard to say how long the rotifers last as 20% or so are exchanged daily.  The slow culture has lasted longer than the warmed, aerated, constantly fed one, which occasionally crashes if I am late with maintenance.  I am not expecting the slow culture to produce rotifers, only to serve as a backup. The other more intense culture produces a gallon or so of about 300 rotifers/ml/day.  It's enough for my needs.
 
Forgot to mention that I use rotifer floss, 6x10 inch piece, rinsed daily at the sink, then sunk into the intense culture.

check out Kathy's Clowns, llc website:
http://kathysclowns.com
Captive bred clownfish and more
(Wholesale to the trade.)

I have had problems lately when changing out culture vessels: When I put the rots into a new container the whole group die off. I then have to re-start that culture from splits from my backup. It eventually gets going and everything is fine. My assumption is that I'm waiting too many days before making the change and the water parameters from culture to new vessel are too different and I lose the animals. I'm working on getting on a better schedule (but I have lots of culture duties and rots are kind of on the low end of the totem pole).

--Andy, the bucket man.
"Not to know the mandolin is to argue oneself unknown...." --Clara Lanza, 1886

I think I've found one of the problems...With all of the splits and near crashes, the salinity got really high.  So I've diluted it back down.  I hope there's enough life to bring the culture back.

Good luck! But yeah, you can't let the salinity get too high. I run mine at the salinity that everything else is in my room (so ~1.025), but that's kind of pushing it. And the shock of sudden salinity changes in really hard on their tiny little bodies.

--Andy, the bucket man.
"Not to know the mandolin is to argue oneself unknown...." --Clara Lanza, 1886

When feeding rotifers, you feed for the amount of rotifers you have.  Going by water volume can lead to massively over feeding, or even under feeding.  This is why counting rotifers is so important.  Sieving 30-40% daily will keep the non productive adults down, so they are not just eating your algae.  They do not effect the production of rotifers in the sense more adults hamper you other then eating all the feed and not producing any you.

 
3 main keys
3) waste removal to keep pH up, ammonia down