Yes if you make your own potting mix or seedraising mix you will want 20 -35 percent pumice sand, or if you cant source pumice sand, then you can use perlite, or washed river sand as a replacement. Most seedraising mixes don't contain fungicide, but they all are cooked/heat treated so they are fungi spore free as well as weed seed free. The pumice sand size you use is relative to the plant size your growing, for seedlings you will want a small grain size so as the seed can easily germinate i.e push though the soil and grow roots quickly. The pumice sand keeps the air to water ratio high, prevents fertilizer build up, and keeps the growing media free draining and light, making it easier for the roots to grow through. If you can't get seedraising mix, you can sieve regular potting mix to a smaller particle size , so you just have the finings for the seedlings and no big chunks.
Seedraising mix recipe
1 part vermiculite,
1 part coir (coconut fibre)
1 part pumice sand/perlite
1 part compost
Sieve each ingredient to a fine size.
(But not the vermiculite)
(If you don't have vermiculite use 2 parts sieved compost instead of just 1)
Then mix well and sieve again.
Then add the vermiculite , mix again.
Add
a sprinkle of blood and bone, sieved dry worm castings and kelp/seaweed powder to provide some nutrients mix well. If non organic, add seedraising slow release osmocote or similar and mix.
Water and then mix once more and then your ready to use.
Although I would still recommend the store purchased seedraising mixes over the home made.
The potting mixture used in the 1st original post in this thread should be fine once the plant is established and at least 15cm tall and the germinated seedling has a semi-root bound seedling pot and ready for up potting. It's more suited to a flowering stage potting mix rather than a seed germination mix as it contains a lot of nutrients more suited to a larger plant.
In saying that every thing should go fine from now on if you reduce time between waterings , keep the leaves dry and remove the humidity domes.
P.s you can lower your light to 60cm (24 inches) above the seedlings as long as your leaves stay dry it won't harm or burn them, currently it's far too high. In a week or two you can lower it a bit more again.
Ok, 5 days later Update....
I have reduced the watering to once every 3 days, I watered last night before lights off (07 May) which is when the soil was looking dry.
Plant (1.) sadly she died, a day after your last reply i noticed the stem turning yellow, this morning (08 May) i opened the tent to see it was lying over dead - not too big an issue, i have plenty more seeds of the strain as well as it being my first grow so i went in expecting not every plant to live.
Plant (2.) True leaves are getting slightly bigger, as well as slight stretching in the stem, but not nearly as much as i was expecting for a 5-day growth period, this morning i noticed the leaves were a bit droopy, but nothing to concern i dont think.
Plant (3.) Hasn't grown a single bit since posting my first post, and compared to my first post the leaves have also started to brown in certain places.
Plant (4.) Plant number 4 has seen good growth, sprouting a new set of true leaves as well as getting a bit taller, but the browning of the leaves is still there.
Plant (5.) Exactly the same as (3.) have seen zero growth and the true leaves are now completely brown compared to the original where just the tips were browning.
The Autoflower in the brown pot is doing amazingly, considering I transplanted it two or so weeks back (it was in regular potting soil outside, but i transplanted it into my custom soil mix and it seems to be absolutely loving it, so once frost season is done i can put her back outside) and i read that X Ruderalis strains dont like to be transplanted.
So all in all there is hope for plants (2.) and (4.). The other two seem to be hanging on by a thread.
If needed i can take some more snaps later this evening when I'm back home.
