The idea with walstad though is that it’s self contained. The plants should be able to survive and ideally thrive in the closed system. All you have to do is add the fish food.

take a 2 litter soda bottle, make a hole on the cap putting thru some airline tubbing, make sure that it’s air tight. the line should be able to go from the floor where you will hide this bottle up and to the bottom of the tank.

place a small air stone at the other end, in the bottle fill 2/3 with mixture of warm water and 1 cup of sugar, add one teaspoon of regular yeast, cap and hide the bottle under your stand. this will provide your tank with carbon for your plants for up to a month.

then all you need to do is empty and fill it again. with the same mixture. your plants will love this and the oxigen production will increase. making an overall healthier tank.

The idea is that the coral/shell replenish the kh and keep the water hard. The chemical reactions going on in the substrate are constantly eating away at this buffer and if it drops too low your pH crashes which is disasterous.

The water I was using at the time was incredibly soft so even with a filter I sitll had to have a bag of crushed shells sitting in one of the filter media basket slots.

I wouldn’t put big chunks of coral or shells into the tank (they might get sharp and dangerous as they erode) but in the substrate should be fine. The only exception I can think of is if you are housing ph sensitive fish in which case you’re probably doing something else to regulate the pH anyway.

I am starting to thing some people are lucky and do not need to cycle their tanks and some like myself and you do. I am hoping to not lose any fish in the process. I took the advice I found and stocked the aquarium immediately. Regret doing it but seeing how it goes.

Thanks for the suggestion!

ie. if a goldfish put its mouth on one and had a munch would it simply tear or are they strong? Might have to do some reading up on them as they look kinda cool.