Algae growing on top of pearlite

Hi Robert , just a quick question, I’m growing in auto-pots outdoors, the last week there is algae growing on top of the pearlite , do I need to remove it and replace the pearlite, it has not affected the ph. of the pots.
thanks in advance

You can put 1 inch of sand . Expensive sand like for children. You need to take away the light from algae . Thats the most natural way. And just wash the sand with ph to your plant and it will be gone.

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@Coltfire … Or you can cut some black plastic circles and use that, I used to use it and it works fine

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The sand keeps out any invader to your soil. Most pest start in soil as larva. Its a very easy trick.

went with the black plastic , as had it on hand , and soilgrowth , I’m growing in pearlite , with hydro solution in auto pots, hydro for outdoors no electricity needed. thank you for your input most appreciated.

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This can be done with any grow. I figured it was hydroponic. Thats why you have algae. With hydro algae goes hand in hand. Its the temperature that makes it grow so fast. With the plastic now you face mold problems.

Even with them growing out doors with natural sun and wind

No matter what.

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Sun in your soil is your worst enemy. Sand good sand can makena huge difference in your grow.

I can grow in sand alone.

Oops…! I wanted to qualify my answer, I used plastic indoors, used it for years with no problem, but outdoors I have no idea

I’ve never considered sand only. What do you do about moisture retention? Do you just increase watering frequency? It DOES seem like it would give better control over nutrients.

Do nothing different. With outdoor grow. Sand drys fast. Indoor needs a little air pointed at soil.


Id love to she this setup sand only loving the idea or since you been using it and it works love your methods


Sand is actually little class granules. Its a great filter so using hydroponic nutes is best so no build up. Hydroponic nutrients are filtered way better.


Not to mention the amount of root branching it should be able to achieve. I’ve been amending my soil with crushed “feather rock” to add the sharp edges needed to split the fine roots.

It’s soft, or brittle enough that I easily hollowed it out with a small chipping hammer.

I wonder what would make the best size grain?


I know what feather rock is, I used to grow in lava rock. I bet feather rock would be a great hydroponic medium ? No? …it’s sharp as hell if I recall but it should almost float in water, it’s so light! I wonder if anyone’s tried it or wonder why not ?

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