bigphil1984

Why is the silica sand green??

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Hi, I planted my cactus seeds on 31/8/17, and the silica sand I sprinkled on top is going green. Why is doing this and will it harm the seeds??bdc381c745583a3fb4543a27d529c826.jpg
 
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It's growing algae at a guess, I don't think it should harm the seedlings.

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Looks like algae development. Water + light + nutrients = algae... quite hard to avoid that equation. You can consider using pure water to reduce the likelihood of algae growing on top of your pot.

As for harming the seeds, if the seeds are big enough, I don't believe it's a matter of concern. It can be more troublesome when dealing with minute seeds like Drosera seeds.

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Looks like algae development. Water + light + nutrients = algae... quite hard to avoid that equation. You can consider using pure water to reduce the likelihood of algae growing on top of your pot.
As for harming the seeds, if the seeds are big enough, I don't believe it's a matter of concern. It can be more troublesome when dealing with minute seeds like Drosera seeds.
Hi Vincent, I've been using clean rain water. The seeds are quite big there opuntia engelmannii seeds, will they be ok? Should I let it dry out slightly?

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It's growing algae at a guess, I don't think it should harm the seedlings.
Hi gaz, do you think I'm maybe spraying it to much?

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Hi Phil,

You're getting algae because you have a surface which has moisture and light. You need the right size gravel, and you need a thick enough layer so their is no moisture on the surface that receives light. I sieved mine out of sand for small seeds like Ariocarpus. But for large Opuntia seeds you could get away with fine gravel, about 3-5mm. They're very robust little growers. And you don't need any humidity, just a soil that gets warm enough during the day.

The humidity alone could allow algae to grow, it could also have grown whilst the soil was damp.

The layer of silica sand is serving absolutely no purpose here !

Honestly Phil, you're mollycoddling these seeds too much! Have you got a sunny windowsill you can leave them on?

Edited by Karsty

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Hi Phil,
You're getting algae because you have a surface which has moisture and light. You need the right size gravel, and you need a thick enough layer so their is no moisture on the surface that receives light. I sieved mine out of sand for small seeds like Ariocarpus. But for large Opuntia seeds you could get away with fine gravel, about 3-5mm. They're very robust little growers. And you don't need any humidity, just a soil that gets warm enough during the day.
The humidity alone could allow algae to grow, it could also have grown whilst the soil was damp.
The layer of silica sand is serving absolutely no purpose here !
Honestly Phil, you're mollycoddling these seeds too much! Have you got a sunny windowsill you can leave them on?
Hi karsty, I give it a good spray off rain water a couple of hours ago and it seems to be disappearing now lol. No where as bad as it was. Maybe not wet enough lol. If I leave them on a windowsill it's worse because of up and down temps.

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Thar's the idea Phil, cacti thrive on higher day temps and lower night temps
Karsty, I have my light on 18/6. I've had other plants on a windowsill, with perlite and the perlite has went green! I started my bamboo off the same time under lights with 50/50 peat and perlite which has no algae at all, seems to be fine. Apart from the silica sand which went green but is now going back white, wierd! My temp through the day is 25-27 degrees, and through the night 18 degrees!

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Try using an organic fungicide, cleared that problem right up for me.
The rain I just collected seems to be clearing it up lol. [emoji6]

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2 hours ago, Karsty said:

The layer of silica sand is serving absolutely no purpose here !
Honestly Phil, you're mollycoddling these seeds too much! Have you got a sunny windowsill you can leave them on?

Hi Phil, I'd tend to agree with Karsty, the sand doesn't really add much here although it does look a bit like a nice gooseberry crumble...yum yum :biggrin:  

I probably wouldn't put them on the sunny windowsill though or at least until they'd developed a bit. 

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Hi Phil, I'd tend to agree with Karsty, the sand doesn't really add much here although it does look a bit like a nice gooseberry crumble...yum yum [emoji3]  
I probably wouldn't put them on the sunny windowsill though or at least until they'd developed a bit. 
Hi gaz mate, I only added sand because it said in instructions when I got the seeds too sprinkle sand on top lol. Lmao it's a chicken tray I got my ribs in from super market lol, I bleached it and sterilised it well enough, with boiling water. Free propergater [emoji38]

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5 hours ago, bigphil1984 said:

The rain I just collected seems to be clearing it up lol. emoji6.png

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I've seen that myself, but believe me it didn't clear up my algae, it just masked it, coming back with a vengeance.

The water does not clear it up in my containers, I think the wetness just makes it blend in and probably thins it out to look clearer, but this means it then comes back from a wider area where the spores have been spread to.

Only the organic stuff that's basically Copper Sulphate, cleared it. But being such a potent ingredient I use it very sparingly, and so far it hasn't had any negative effect on germination, with the added benefit that it also combats damping off disease.

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5 hours ago, bigphil1984 said:

The rain I just collected seems to be clearing it up lol. emoji6.png

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I've seen that myself, but believe me it didn't clear up my algae, it just masked it, coming back with a vengeance.

The water does not clear it up in my containers, I think the wetness just makes it blend in and probably thins it out to look clearer, but this means it then comes back from a wider area where the spores have been spread to.

Only the organic stuff that's basically Copper Sulphate, cleared it. But being such a potent ingredient I use it very sparingly, and so far it hasn't had any negative effect on germination, with the added benefit that it also combats damping off disease.

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I've seen that myself, but believe me it didn't clear up my algae, it just masked it, coming back with a vengeance.
The water does not clear it up in my containers, I think the wetness just makes it blend in and probably thins it out to look clearer, but this means it then comes back from a wider area where the spores have been spread to.
Only the organic stuff that's basically Copper Sulphate, cleared it. But being such a potent ingredient I use it very sparingly, and so far it hasn't had any negative effect on germination, with the added benefit that it also combats damping off disease.
What products can you buy?

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2 hours ago, bigphil1984 said:

What products can you buy?

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We have local organic brand called Copper Count-N.

The liquid is blue and very little is needed per application.

For general algae issues you can get some Yellow Sulphur (chemist shoukd have) then just google a bit for dosage strength. Flowers of Sulphur is also a very good anti-bacterial and anti-fungal that can be applied in it's powder form to cuts on succulents and cacti like where you took off a pup or took a segment to grow a new plant from.

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