Tank Cycle Queerie

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Hi All looking for help advice I am currently cycling a 40gl fish only tank been running for 13 days now previously used as tropical, I am using two mollys in process I know not nice but lfs advice, wish found ac earlier, any how i have 13lbs of live rock in there seems to be doing well lots of things growing on it but marble chip substrate is turning brown as you can see in photo. Also reading other posts about amonia spikes etc mine only got to .50 now down to .25 nitrite is 0 ph is 8.2 and temp is 78 sl 1024 filter is 3 stage in hood with 100l per hour pwr head or 265gl if easier is this norm if not how can i fix.
any help much appreciated

Reefscape said:

The brown algae your experiencing is diatoms, perfectly normal with a new aquarium, happens to all new systems....

The ammonia, level, well, you already know the downsides now with using fish to cycle....so, no more need to be said..Regarding creating an ammonia source, i would suggest the two mollys wont create enough ammonia to get a decent spike..I would suggest you add a raw shrimp or prawn in some pantyhoes or fine mess bag, suspend in the aquarium and allow it to rot away...This will produce the much needed ammonia...When ammonia reaches about 4 - 5ppm, remove it and let the cycle continue...

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Thanks Reef Scape will do I also have tropical tank should i put mollys in there to save them more stress