Help keeping rotifers (SOLVED)

[Armadus]

I've been banging my head against this problem and can't take it anymore.

I am able able to keep a rotifer culture going for two weeks max. After that, the culture turns yellowish brown and I see no rotifers when I go to collect them. I've been working around this by purchasing 1mill from Reed a day or two before a hatch but it is getting too expensive.

The culture is in a 5g bucket with a heater, rigid airline, and hanging rotifer floss like reed mariculture suggests. The heater is set to 78. The salinity is 1.019. The airline is creating large bubbles. I am feeding RG Complete, 3ml in the morning, 3-4ml at night. I skip feedings if the water looks green. At first the culture does great, but eventually it turns to poop.

I've been collecting rotifers (every morning) by filling a pint glass and pouring it through a fine mesh (53um) so that the water returns to the culture. I do this 5-6 times so that ~20% of the water has gone through the mesh. With the batch I currently have, I replace the water during collection with dechlorinated tap water at 1.019 that has been bubbled for at least 12 hours and same temperature as the culture.

What am I doing wrong? Am I collecting too many and thinning the population? Should I do more frequent water changes?

[chuggy]

your really doing everything right you should be able to harvest 1/3rd of your culture daily. make sure everything's sterile air lines rigid line bucket, heater.

[Scottt]

I've been collecting rotifers (every morning) by filling a pint glass and pouring it through a fine mesh (53um) so that the water returns to the culture. I do this 5-6 times so that ~20% of the water has gone through the mesh. With the batch I currently have, I replace the water during collection with dechlorinated tap water at 1.019 that has been bubbled for at least 12 hours and same temperature as the culture.

What am I doing wrong? Am I collecting too many and thinning the population? Should I do more frequent water changes?

Try not returning the sieved water to the culture. The culture should get new saltwater to replace the 20-30% you take out daily. Also, I find it best to harvest all day, then replace the water at the end of the day. This way you get a larger percentage water change, if you know what I mean. The rotifers seem to prefer cleaner water over consistency. I often start a culture with 100% new water and sieved rotifers, they love the clean water.

When you take the airline out, and shine a flashlight in, can you see the density of rotifers? If you are slowly depleting it, you will notice a slow reduction in density. If it stays really dense and then goes clear one day, it crashed. Crashing is usually from inadequate water changes, or inadequate feeding. You probably know this, but if the culture increases in density, you need to feed more algae. Personally I have much better luck feeding the cultures so that they stay green (when looked at with a flashlight shining in the culture), rather than going with a certain miiliter amount of algae. I always crash cultures by not adding enough algae when I try and do the ml thing. Just keep in mind that a dense culture will look slightly brown without any algae, it's more the depth you can see into the water, and the color green that you look for.

Also, I'm not sure how well the floss works, but we find it best to transfer the culture to a new bucket once a week. We just take the airline out for about 60 seconds, then pour the culture into a new bucket, leaving the gross stuff at the bottom behind.

[Armadus]

Thanks for the replies!

When I first get the rotifers, the culture is very dense when looked under a light. As time goes on, the culture gets thinner and thinner even though the water is green. This is especially noticeable when I strain them to feed to the fry. On day one, it takes two, maybe three pints to get a good amount. On day 7 it takes 8 or 9 pints to reach the same count.

I always try to keep the water slightly green and if i see it clear I add more RG complete than the previous time. I do often see that the water is clear, mostly in the mornings. I know that when food becomes scarce, the culture is overcome with males which cannot reproduce. How long does it take before this happens? A few hours? Could this be the reason?

This morning I ran the entire culture through a sieve and emptied the sieve into a fresh bucket. I added enough RG to get the water neon green. Hopefully there were a few eggs in there which will hatch and restart the culture...

Would you recommend feeding more? Less? Unfortunately, I cannot feed them during the day so twice a day is my only choice.

I'm editing this post because I just read something interesting. In Reed's culturing rotifers section they say 500 rotifers/ml is a low density culture. I have no idea if this is a mistake or if I'm WAY WAY WAY off. I have a plastic syringe that I use to carry RG Complete from the fridge to the bucket. After adding the RG, I fill up the syringe (12ml) and I'll be lucky to see 30-50 rotifers in it.

I must be trippin'...

[rayjay]

To be honest, I think there has to be more than one way to succeed because I do it different than others in that I use 5g inverted water bottles with the bottoms cut out, and using inverted two litre pop bottles as back up supply in case of a crash.
My crashes normally happen when I get lazy and don't clean out the container soon enough.
In my case, I only harvest when I need them as I only need them for the first four weeks of a batch of seahorse fry. I feed a new culture on live nanno for about a week but after that I use greenwater made up with spirulina powder (and some Algamac 3050) in water, blended for at least 2 minutes and I store in a pop bottle in the fridge to use as needed.
I usually add smaller amounts two to three times a day rather than just a larger amount once a day which seems to dirty the culture much faster.
When I'm harvesting for fry, I keep the water cleaner so the rotifers aren't ingesting too much detritus/excrement and instead are feeding mainly on the nutritious spirulina and Algamac 3050. This way they are always enriched when I feed them to the fry.
I'm not so critical about cleaning the water when I'm not harvesting them as I'm only keeping the culture going, not needing a nutritious product.
I don't understand why you are seeing so few in your culture as when I use a syringe to check the culture, it is a way too dense for me to even try to count.
My biggest problem with rotifers is that they somehow migrate to other rooms where copepods are under culture, and they overtake these cultures.

[Scottt]

I like what RayJay has to say. Everyone has different methods, you just have to find one that works for you.
+1 about them crashing when one doesn't clean out the container. That is my experience also.

If you put 1million rotifers in a 5 gallon bucket you'll start with around 60 rotifers/ml. Somewhere between 60 and 200 per ml seem to be where my cultures run. If you have a syringe that can do a ml or a part of a ml; take a half a ml or so and squirt it on a reflective surface (I use the screen of my tablet), put it under light, you can count the rotifers. Keep a log of it, maybe take some photos.

I think adding more algae would be a good idea if you are having issues and the water is clear often. Make sure you change out a consistent 20-30% of the culture water daily (8 or 9 pints) with aged newly mixed C2O. But give it maybe 3 days in the 5gal bucket to grow before you start doing your WC's or harvesting. So on day 3 or four, start harvesting by taking 8 or 9 pints out, and pouring them through the sieve, discarding that water, and adding aged newly mixed saltwater to the culture. Be sure to change out buckets once a week also, leaving behind any goo on the bottom.

In serious commercial rotifer production they have them crazy dense like they are talking about. To them 500/ml is probably low density, idk.

Also, temp doesn't matter that much, but at 78 the culture will be at pretty much peak production, and use up algae the fastest, but grow the fastest.
You could try dropping your SG down to 1.015 (in addition to the increased algae feedings). I'm not sure what your issue is, but they do grow better at 15 than 19 I think.

[rayjay]

I didn't mention that mine are in 1.017 water and are grown at room temperature which is always 68°F.

[Armadus]

Thanks for all the replies! I actually called Reed and spoke with someone who figured out my problem. If you are using RG Complete, it takes 11ml to "make" 1 million rotifers. My problem was that I was WAY underfeeding them, hence why my culture would get thinner and thinner. The interesting key to all this is you control your culture density by harvesting, not limiting food.

I'm still working on balancing food vs. collection but I can safely collect 1/3rd of my culture daily and not run out after a week.

I really hope this helps someone in the future.

Thanks!

[lizardlady]

Hi. I have the same problem. I get the rotifers a few days before baby clowns hatch, and the rotifers do great for about five to seven days. I use one gallon jugs and the rotifers turn the water clear within one day at first. I use home grown greenwater and add half the amount of the rotifers from clear jug. The rest get fed out or put in another jug with new greenwater. I have found that strangely enough, the rotifers don't do as well in the mature dark greenwater (nano) as they do in slightly lighter water. I am frustrated because I can't keep cultures going for more then one week before they peter out and crash. I have tried saving the gunk from the bottoms of the crashed jugs but no results. I have tried using simply rinsed jugs and sterilized jugs, four gallon buckets, high aeration, low earation, adding some old culture water, always with the same result. I use r/o d/i water and my greenwater is healthy. My keep my ph at 6.5-7.5 with salinity at .0014. I have read the culture manual from front to back but I am missing something. Any ideas?

[lizardlady]

Well, after experimenting I have worked out a system which works for me. I start a 1/4 gallon of greenwater about two days before I expect babies. I stabilize the ph from 6.5 to 7.5. After 24 hours I add a small amount of rotifers. Each day I start another culture and so on,,this method produces large batches of rotifers and I have found crashes happen a lot less often. I also have a four gallon bucket of "back up" rotifers that I feed sparingly with greenwater. I change 1/4 of the bucket every day by siphoning the bottom. I have found that rotifers really don't seem to like any sudden changes in ph or temperature either. It seems like a lot of work to maintain these little critters but when you are looking at a few hundred little hungry mouths and you are out of rotifers you realize it is all worth it!

[natureAddict]

Interesting methods to culture rots ).
Question- if my culture is thin, can I don't water change, add nan paste
daily until it's more dense?