Help with my 7 week SW tank

[klm]

I'm probably doing a lot wrong but I could use some guidance. I set my 40 gal. saltwater tank up 7 weeks ago. It has 5 pretty good size pieces of cured live rock inside. I left it alone for about 2 weeks with the live rock then I added a clown fish and a blue damsel, they both seem to be pretty peaceful and doing great. Two weeks later I added a chocolate chip starfish it seems to be doing well also. About the 5th week I thought the tank had fully cycled so I added a Lawnmower Blennie, he seemed content and I saw him eating and chomping on the live rock daily. Friday I bought a dot-dash butterfly fish. Well Saturday morning (after having him about 2 weeks) I woke up to find my Blennie dead and late last night the butterfly fish was dead.
The ph in the tank is 8.2 the nitrates are 20ppm, not ideal but still safe. (I can't seem to get them any lower) Nitrite is 0 alkalinity is about 300 ppm. My hydrometer measures between 1.021 and 1.022.
I'm sure I'm making mistakes but not sure what they are, any advice would be appreciated.

 

[epond83]

What is your ammoinia level?
How many bs is '5 pretty good sized pieces'?
I think your salinity might be low, i don't know enough to be a lot of help but the stickys in this section are a big help. Also what equiment you have on the tank would help.

 

[GlaringToast]

Try to bump the salinity up to 1.023 by replacing a little bit of evaporation water with Saltwater instead of RO. It's low but not low enough to cause a problem for any of that stuff. GET RID of the chocolate chip starfish. They are not reef safe, they can and will be aggresive towards fish and corals. Your nitrates being high is most likely from a lack of live rock as filtration, I'm assuming. Also do you have a deep sand bed? Any kind of Clean up crew?

 

[klm]

Here's a bit more information. My sand bed is a mix of crushed coral and sand, it's about 2-2&1/2 deep. I checked the salinity again and it is right on at 1.022.
For filtration I have inside the tank a Fluval 4 plus, inside it has 2 sponges and 1 carbon sponge. I don't have a power head in the tank but I was told I didn't really need it unless I was going to keep corals. I want to keep it simple the first year. The flow in the tank looks pretty good. I see alot of water movement.
It's hard to say how much live rock I have, 3 big pieces and 2 smaller ones. My guess would be about 40 pounds. Any ideas?

 

[GlaringToast]

Ditch the Chocolate Chip. I would suggest a small powerhead to eliminate any dead flow spots you may have in the tank. I would ditch the sponges in the fluval, throw in some filter floss (polyester or double sided filter material blue on one side white on other) You can run carbon if you want. I would suggest changing out the filter media every 3-5 days. You could also buy some rubble rock and fill the filter with that or a combination. Also I would try to get a little more live rock especially if you're unsure of how much you have. Overdoing it is definitely a much better option in this case. I would suggest a few nassarius snails to stir up the sand bed and eat all the crap in there along with some snails to janitor your tank a bit. For the long run I would start considering a sump and a refugium as these will GREATLY expand your options for filtration and your tanks tolerance to ammonias, nitrites, nitrates, phosphates, ect.

 

[klm]

Thanks for the advice. For starters I'm going to change out the medium in my fluval to the floss as you mentioned. I haven't cleaned it at all in a few weeks since it was newly cycled I thought I should leave it alone for awhile. I'll add a few more pieces of live rock, the snails and add a power head. I'll have to wait on the sump, I can't afford that right now. Do you think I lost the two fish due to my nitrates being just a little bit high? I really don't think the choc. chip bothered them.

 

[GlaringToast]

Nitrates don't affect fish, it's ammonia that kills fish. I would imagine you have a pretty good ammonia spike, maybe from adding so many fish so quick, it's hard to tell for certain. Keep up with changing out the filter media (as much of a pain it really can be) do your water changes and add some live rock and you'll be fine.

 

[klm]

Another question if you don't mind so many I was looking online for a power head and there are so many choices. I can't see anything that recomends the size I need for my 40 gal. I'm looking at a Koralia 2 Aquarium Pump 600gph and the Seio super flow 620gph. Do you know anything about either of these? I need something fully submergable since I have a canopy top.

 

[quaddity]

I like Koralias that's what I run. A couple #2s will definitely put some flow in there. Get rid of the Fluval too. All you need is 1-2 lbs of live rock per gallon, some powerheads for circulation, and preferably a protein skimmer. A sump is not a required but nice to have. If you keep the Fluval plan on cleaning it every few days.

 

[Lorna]

Also not mentioned is to rethink your substrate. Crushed coral will trap detritus and create high nitrates. You should think about switching this to straight sand......crushed coral should be banned from saltwater......one of the second greatest nitrate sinks next to cannister filters and bioballs.