Harvesting pods/rotifers

[Steve Morse]

Hiya

A quick question regarding harveting roti/pod cultures. In am intending to draw 1l from a 3l culture solution. Once the 1l has been removed (without filtering) it is reduced to 50ml by siphoning using a 53 micron filter. Using this approach means the roti/pod are not exposed to air.

Q1 is this approach OK in terms of reduction from 1l to 50ml

Q2 does the 50ml need to be aclimitised prior to adding to the tank to ensure survival if not eaten as I am trying boost general pod life as well as provide direct feeding.

Many thanks

Steve

[FUGU]

Hi Steve

A1: volume reduction is no problem just be gentle to avoid crushing the critters against the mesh with too fast a flow; if you have the large 53 micron strainer this will be less of a potential issue.

A2: temp shock and osmotic stress are potential issues - providing the values are within 3% of each other you should be safe for the critters to be happy.

Re pods and temp our strain doesn't like the water temps going over 30 deg C - if the temp is kept to 28 max you should be safe.

Your other order went out today. I've delayed the phyto shipment until later this week I hope that doesn't cause any inconvenience!

Cheers

[Steve Morse]

Thanks Fugu

As always the answer to one question leads to another....

I keep the main tank SG at 1.0250/1.0260 and 25ºC. The literature advises to maintain the culture at 1.015/16 is there any problem with increasing this to 1.0250?

Delivery of phyto is OK

Cheers Steve

[FUGU]

Hi Steve - OK the salinity difference is quite large and relates to a salinity difference of between 22 and 34 ppt. In this case I suggest you could raise the salinity of the harvested pods over a period of 24-48 hrs using your tank water to bring the salinity up.

A 1:1 mix of culture salinity and tank salinity should bring the salinity from 22 to 28 ppt (SG of 1.016 to 1.02)
A further equal addition of tank water salinity should bring the salinity from 28 to approx 33 ppt (SG of 1.02 to 1.025)

I think those figure work - sorry if not as I've just jotted them down!

Cheers

[tontikki]

i know the literature advise it, but why so low salinity for cultures? i'm trying to keep salinity in my culture similar to the tank water, about 35ppt. they seem to be doing ok:confused:

[FUGU]

Hi tontikki. My guess is that the various species have adapted to the food conditions e.g. the coastal/brackish waters being food rich with more phytoplankton and organic detritus available? For artemia the cysts come out of hibernation when the salinity drops in their salt lakes and algae blooms following the rainy season; I haven't checked the salinity figures normally recorded but its an evolutionary development to take advantage of the seasonal blooms/lower salinity - perhaps this is too extreme an example? I'd say keep going with your protocol if you're getting enough. A cut in 1/3 of the salt required for the cultures is an attractive bonus for us.
Cheers