Absolutely terrible feeling, isn't it. Everything felt right, but it never went anywhere.
Here at Aquaculture Kings, we're all about sharing knowledge. Our mission is to lift the live foods industry, so we're more than happy to pass on what we've learned over the years.
If the below doesn't help you, reach out on social media and we'll help you troubleshoot.
Below are the most common reasons cultures crash, ranked from most to least common.
Phytoplankton: top causes of crashing
Salinity too high or too low. Some strains are very particular about the salinity they'll thrive in. Do your research on the strain you're culturing. If salinity is too high, add RODI water in small amounts until you're back in range. If it's too low, pre-mix some high-strength saltwater and add it in small amounts, checking between additions.
Underfeeding or overfeeding. Underfeeding starves the cells. Overfeeding promotes bacterial growth, nutrient imbalance, and pH instability. Follow the dosing instructions to the letter.
Bad water source. Old or stagnant water, especially from uncirculated drums or sun-exposed containers, can be toxic. Use freshly mixed saltwater. Avoid natural seawater unless it's been sterilised.
Temperature. Phytoplankton grows best around 24 to 27°C. Lower temperatures slow cell division and gradually starve the culture. Higher temperatures rapidly kill the cells. The only safe heater for phyto is a reptile mat. Never submerge electrical heaters or probes in a culture.
Starter culture was already dying. Some strains have a short shelf life. All strains have telltale signs based on colour. Healthy Nannochloropsis is a deep dark green. As it starts to starve, it turns brownish. Once it's dying, there's no green left at all.
Contaminated air source. Your air pump should sit in an isolated area. Ideally the air is filtered, or sits near an air purifier. Bug spray, air freshener, or any unidentified airborne particles can wipe out a culture in hours.
Stale fertiliser. Guillard's F/2 should go back in the fridge immediately after every use to prevent bacterial growth. Left out, the nutrients begin to clump and foul the bottle.
Give it another shot with high-purity phytoplankton you can rely on (provided you've nailed the points above).
Zooplankton: top causes of crashing
This includes copepods, rotifers, ciliates, and the rest of the little creatures.
Ammonia build-up. Yep, these guys can produce enough ammonia to knock out their own culture. We always test our zoo cultures no matter how confident we are. Weekly harvesting matters even when you don't strictly need the harvest. Aim to replace at least 50% of the water to keep waste in check.
Salinity. If salinity is too high, add RODI water in small amounts until you're back in range. If it's too low, pre-mix high-strength saltwater and add it gradually, checking between additions.
Overfeeding or underfeeding. Overfeeding isn't always a problem if you keep up with weekly water changes. Underfeeding tanks reproduction and kills the culture. Look at your cultures daily. If the water is perfectly clear, they're probably starving. We use the same Ultramix Phytoplankton formula in our own zoo cultures.
Bad water source. Old or stagnant water, especially from uncirculated drums or sun-exposed containers, can be toxic. Use freshly mixed saltwater. Avoid natural seawater unless it's been sterilised.
Temperature. Aim for a stable 25°C. Most zooplankton are fine in the 20 to 29°C range, but reproduction rates drop the colder it gets and climb with warmer water. Just remember that warmer water also promotes bacterial growth, so don't push it.
Don't give up. We've got the cultures and live foods you need to start again.
