My 10 gal planted shrimp tank had an explosion of hydra from my LFS pearl weed. I first noticed them 2 weeks ago spread across almost everything in the front of the tank. I check the tank every day and didn't see any before (they're green so I probably missed it when there were less). They are concentrated on parts of the spiderwood and the glass, and when the population gets really large they start growing on the plants. It doesn't seem like they really spread much beyond the front right of my tank, I sometimes see a couple on other plants.

I'm a student and just had to pay tuition, I desperately want to save my baby shrimp but can't afford to buy dog dewormer for the 7 week recommended period at $25 per week. I don't want to get fish that eat the hydra because then my babies would be toast. My other tank has big harlequin rasboras in it so I worry about moving the shrimp. I dosed with 68 mg praziquantel today and have enough for one more dose. I removed my carbon filter and just have a sponge filter now. 

The hydra population briefly dipped by maybe 1/3 (having made no changes to the tank) but bounced back a couple days ago. I have 4 surviving shrimp babies and they're growing very fast but I'm still terrified.

pH: 7-7.2 (crushed coral in tank)

Temps: 75-76F, occasionally 78-80 for 4-5 hrs because we don't have AC

0 ppm ammonia and nitrates

Tank has been up for 4 months, shrimp added 1 month ago

Pest snail population has very significantly decreased in the last 1.5 months with me only occasionally removing a few, netherite snails have almost completely vanished (ramshorn pop decreased by maybe half?).

Fertilized once a week

20% water change and vacuum substrate 1x per week

There is still a little bit of biofilm on the spiderwood after maybe 1.5 months of having it.

No significant algae problem, sometimes hair algae if I leave the light on too much

Cheapest way to remove hydra- trying to save shrimp ASAP