Those seashells can really buffer the pH and water hardness to a intolerable amount unless they're plastic or something. I'd take them out unless you have a ridiculously low pH tbh.

I cheched my pH and I washed hell outta them. They seem to be ok. If anything goes bad then I will take em out though.

People use sea shells and shell based in african cichlid tanks to bring the pH to 8 or higher. Given your don't have a lot of them, the course isn't going to be immediate. But having a steady pH is the most important thing in an aquarium, and unless you have black water fish or african lake fish, you really should have pH neutral decorations only. Otherwise doing water changes may put your fish into pH shock, which imo is the worst way for a fish to die.

Mmm, thanks for letting me know Oni ^^

The way it works is like this, regardless of how washed the shells are

Shells and aragonite based sand (aragonite based is just crushed up shell, basically) deteriorate in acidic water, so when the water is below 8.0, they melt away quickly, this makes the water more alkaline and hard (I'm no chemist, but this is the effect, don't ask why it's the effect) once the pH is really up there in the 8.5 or so, it'll stop deteriorating.

The hardest part of taking care of african cichlids is that if you do a big water change in their tank with aragonite based sand and/or seashells, the pH will rather quickly drop back down to tap water level, which in america tends to lay around 6-7.6 depending on the city water. The sand doesn't instantly change the pH as it enters the tank, so water changes have to be around 10% a week, at a very slow and steady pace.

change in nearly 1.0 pH, or even a change of as low as .5 pH, will be the equivalent to the fish as if somebody jabbed a giant syringe into your blood stream and started pumping it full of water. The change in pH, hardness, or salinity at a fast pace causes too much (or not enough in some cases) water to enter the blood stream. usually the fish will jolt from corner to corner, usually hard enough to break its skull on the glass from the shock (that's why it's called pH shock)

I don't mean to disgruntle, but keep in mind that aquariums are very fragile, enclosed ecosystems, everything you put in or take out of the tank can take a tole on the fish that live inside of it.

oh, and here are my two main tanks if you were curious

http://www.furaffinity.net/view/7830000/
http://www.furaffinity.net/view/7754544/

I took them out o.o and I looked it up cause I was curious. I am glad that you let me know about it or I wouldn't have known.

My tank looks fine without them and they only cost me $1 lol. No biggy. Ill just buy fake ones some time.

fishy fishy fish ^^

FISH FISH FEEEEEESH! XD

I LIKES YOUR FEESH TANK!