Tools
Calculators
Five questions keepers ask, answered by the same model as the culture simulator. Each answer shows how it was worked out, and a range, because the model is a set of stated assumptions and not a measurement.
The data for the calculators could not be loaded. The answers below are still right for the situation they describe.
Your answers
How many springtails to add to an enclosure
Add springtails before the other animals, so the population has time to settle. Settled means half of what the enclosure holds.
Add about 160 springtails.
That settles inside 4 weeks in most runs.
| Start with | Settled in time | Weeks to settle |
|---|---|---|
| 10 | none of the runs | 8, most runs 6 to 10 |
| 20 | about 1 in 10 runs | 7, most runs 5 to 8 |
| 40 | about 1 in 10 runs | 6, most runs 4 to 7 |
| 80 | about 4 in 10 runs | 4, most runs 3 to 5 |
| 160 | about 9 in 10 runs | 3, most runs 0 to 4 |
| 320 | nearly all runs | Already settled |
| 640 | nearly all runs | Already settled |
How this is worked out
The model starts a population of each size in an enclosure that holds 0.5 animals for each cm² when full. A start settles in time when the population reaches half of that inside the weeks you gave. Each size is tried in 16 runs with the uncertain figures varied, and the table gives the share that settle. A bought starter is a few hundred animals.
How much to feed
Dry yeast is the usual food. Too little starves the culture. Too much goes mouldy and draws mites.
About 130 mg of dry yeast at each feed.
About half a pinch each time. Fed 2 times a week, that is 250 mg of dry yeast a week. Each feed holds about 4.2 days of what the animals eat.
Over 26 weeks the model rates mould risk low and mite risk low for this schedule.
| How much each time | Dry yeast | In pinches | Lasts |
|---|---|---|---|
| Light | 53 mg | About a quarter of a pinch | 1.8 days |
| Matched | 130 mg | About half a pinch | 4.2 days |
| Generous | 230 mg | About one pinch | 7.7 days |
| Heavy | 420 mg | About 2 pinches | 14 days |
As the culture grows
| Animals | Dry yeast | In pinches |
|---|---|---|
| 100 | 13 mg | Less than a quarter of a pinch, a few grains |
| 300 | 38 mg | About a quarter of a pinch |
| 1,000 | 130 mg | About half a pinch |
| 3,000 | 380 mg | About 2 pinches |
How this is worked out
An animal is taken to use 0.03 mg of dry yeast a day. Each feed holds 0.5, 1.2, 2.2 or 4 times what the animals use before the next feed, for light, matched, generous and heavy. A pinch is taken as 0.2 g, about a sixteenth of a teaspoon.
How many you can harvest
A culture stays steady when it grows back what you take. Steady here means that in most runs the animals at the last gathering are at least four fifths of the animals at the first.
Wait until week 9, when most runs have reached four fifths of a full culture.
Every week
Take up to 20%
About 320 animals each time, and 17,000 a year.
All the shares tried
| Share taken | Each time | A year | Holds steady |
|---|---|---|---|
| 10% | 180 | 9,600 | Yes |
| 20% | 320 | 17,000 | Yes |
| 30% | 310 | 16,000 | No |
Every two weeks
Take up to 40%
About 720 animals each time, and 19,000 a year.
All the shares tried
| Share taken | Each time | A year | Holds steady |
|---|---|---|---|
| 20% | 400 | 10,000 | Yes |
| 40% | 720 | 19,000 | Yes |
| 50% | 610 | 16,000 | No |
Every four weeks
Take up to 70%
About 1,200 animals each time, and 16,000 a year.
All the shares tried
| Share taken | Each time | A year | Holds steady |
|---|---|---|---|
| 40% | 820 | 11,000 | Yes |
| 70% | 1,200 | 16,000 | Yes |
| 80% | 750 | 9,700 | No |
How this is worked out
The model tries each share at each rhythm, starting at the week most runs are ready, and keeps going for 26 weeks. A share holds steady when, in most runs, the animals at the last gathering are at least four fifths of the animals at the first. It tries 16 runs for each.
When to split a culture
Split when the culture is nearly full, so you take many animals and the parent recovers soon.
Split in week 9.
The middle culture is ready in week 7. By week 9 about three in four are.
| You take | Animals | Parent is ready again in | New culture is ready in |
|---|---|---|---|
| 25% | 480 | 1 week | 6 weeks |
| 50% | 960 | 2 weeks | 4 weeks |
| 75% | 1,400 | 3 weeks | 3 weeks |
How this is worked out
The model finds the week three in four runs reach four fifths of a full culture. It then takes the share shown, and times how long the parent takes to get back to four fifths and how long a new culture takes when it starts from the animals taken.
How many cultures you need
Your cultures supply the enclosures you keep. The count covers the first seeding, the top-ups after that and a spare in case one culture fails.
Keep 2 cultures.
1 supplies your 4 enclosures. 1 is a spare.
- Seeding each enclosure takes about 160 animals.
- Topping up about 2 times a year, at half of that each time, brings the total for 4 enclosures to about 1,300 animals a year.
- One culture gives about 16,000 animals a year when you take up to 70% once a month.
- Start the first culture about 9 weeks before the first enclosure, so it is ready to split.
How this is worked out
Each enclosure is seeded with the number above. Animals that hunt springtails mean topping up more often, as the animal you chose does. A quiet enclosure needs one top-up about every 26 weeks, and each top-up is 50% of the seeding. The cultures needed is the animals needed in a year divided by what one culture gives in a year at its steady harvest, rounded up, plus 1 spare.
What the calculators assume
The calculators use the simulator's model and add the rules below. The simulator page lists every figure the model uses.
- Model assumption The seeding table treats an enclosure as a culture that holds 0.5 animals for every square centimetre of floor once settled, far fewer than a culture tub. It counts a start as enough when half of that has been reached within four weeks, which is the three to five weeks sellers say to leave before adding other animals. A vivarium with less food usually settles more slowly than the model says. Open question How many springtails does a settled enclosure hold?
- Model assumption Where nothing eats the springtails, an enclosure is topped up every 26 weeks. Each animal that does eat them divides that time by its reseed factor. Each top-up is half the first seeding. Keep one culture beyond what the harvest needs, so a failure never leaves none, because sellers warn that a culture drained too far takes weeks to recover. Open question How often does an enclosure need more springtails?
- Model assumption A harvest is steady when, in three runs of four, the culture holds at least four fifths as many animals before its last gathering as before its first. The first gathering waits until three quarters of cultures are ready. Animals taken are the ones you can see, adults and young, and never eggs. Open question How fast do keepers' cultures really grow?
Sources
- 1
Springtail Care & Breeding Information
New England Herpetoculture
Link works · Retailer
Cited at Seeding a vivarium; Using springtails as feeders.