Iorek, you have several options. I will try my best to list them all.
1. Get some glasses.
2. Use a magnifying glass.
3. Tell someone else to check for you.
4. Too much tannin water can be dangerous... In theory. So lighten up on that just to be safe, and so you can see what lives in your spawn.
5. Repeat from step 1 once you get here.
If you can't see, how do you think you will know how much to feed. Let's say I told you to feed only 100 bbs, then what? Lol. Anyway, you will need to see these little tadpoles to know how much to feed. Over feeding and underfeeding both result in bad consequences. I personally never thought about how much I feed them, it's just a feeling of... "Okay, that's enough" lol. Each fry size varies, that's why you have to take into consideration the variations that works for one person and not the other. Use your judgement according to fry size and food size. This is best learned by trial and error. Be sure to document so you don't repeat the same mistakes or worst, give up. Good luck! Hopefully this helped you. Maybe someone else can donate some advice to you.