120 Gallon Build Thread

[Lisa Cain]

Dear Reef Family, I am posting my build thread. I just found out how to do this, therefore I am posting my most recent update and then providing information and pictures from pre-set up until now. All of the questions in my post have been answered in prior conversations with the Reef Family.

1/4/2026 26 days post set up
Thanks to all.
Deer Reef Family. I made the transfer and all is well. I am posting the new pictures. Three weeks and 5 days of cycling. The fish are much happier. Coral are happy including my large bio cube. Now all I have to worry about is not overfeeding and raising nitrates or ammonia to high. Ammonia is currently zero and Nitrates 5 ppm. Alkalinity is 7.7. The owner of Exotic Reefs in Cypress, Texas came over and helped me to improve the design of my aquascape.


Pre-Set up

Dear Reef Family, I am upgrading from a 65 gallon Red Sea 250 all in one to a 120 gallon aquarium. It is a little scary because it is a much larger tank and I have never used a sump. I apologize for bothering everyone again but I trust my Reef Family in regards to advice. Please look over what will be in my tank so that I can make changes if necessary. I have already ordered everything, however I still may be able to switch out things. The tank will not arrive to the shop until December 10, 2025.

Tank Details
Tank - Planet 120 Reef 48.5 x 24.5x25
Sump -Sapphire 34 ( I was getting the Tideline Sump 30 x 16 inches but I would not get it in time)

• Dimensions: 34" long x 15" wide x 15" high
• Skimmer Section: 10" x 14"
• Center/Refugium Section: 10.25" x 14.5"
• Return Pump Section: 6" x 14.5"
• Total Water Volume: 31 gallons
• Skimmer Water Level: 7" to 9.5" adjustable
• Drain Input Fittings: 2
• Drain Input Fitting Size: 1"
• Filter Socks: 2

Pump: Sicce Syncra 5.0 Aquarium Pump -1321 gph
Sand-Caribsea Arag-Alive Bimini Pin 20 lb
Kessel A360XE-TB Tuna Blue LED (2) (Still trying to compare the AI Prime and Hydro Light. Are there problems with the Kessel
Kessil AP700 Mounting Arm
Eheim Jaga Heater 125W
Classic Stand 48x24x36
Planet 120/140 Glass Top 3 pc set. I decided to save money and not get a wooden canopy

Thanks for you input! Below are my tank inhabitants. They are just waking up and expecting their morning feeding. Attached is a picture of my bubble core after fully opening. It is also just waking up in the first picture.



Hello my tank has cycled, working on th4e diatoms which seems manageable. I am working hard on raising alkalinity from now 6.7 to 8.5. This is keeping me from transferring the remainder of the fish and corals. I am dosing with Seschem fusion 2 and All for Reef. Lesson for new reefers! If a company is setting up your tank please ask for the parameters of the water. The water that was used for my 120 gallon tank was completely off parameters! Now I am trying to fix it

Day One Set-up December 10, 2025
Hello Everyone,
I want to share the progress of my new tank. I am excited to have an upgrade from the 65 gallon Red Sea Max all in one. The hard part was having to take out the rocks and most of the water from my old tank so that they can move it to the side. I still have it and all of my tank inhabitants are in it. However, they went through a very stressful period. It seems as if everyone is okay. I was so busy trying to take care of the old tank that I did not watch everything that they did with the new tank. I transferred live rock from my old tank and about 12 gallons of water from my old tank. I have to figure out how long it will take before I slowly add to the new tank. Some people transfer quickly.

I have to read about how to set up a beautiful display. The water in the new tank was almost clear last night. I like the fact that there is very little noise.

Tank Details

Tank - Planet 120 Reef 48.5 x 24.5x25
Sump -Sapphire 34
Dimensions: 34" long x 15" wide x 15" high
Skimmer Section: 10" x 14"
Center/Refugium Section: 10.25" x 14.5"
Return Pump Section: 6" x 14.5"
Total Water Volume: 31 gallons
Skimmer Water Level: 7" to 9.5" adjustable
Drain Input Fittings: 2
Drain Input Fitting Size: 1"
Filter Socks: 2
Pump: Sicce Syncra 5.0 Aquarium Pump -1321 gphc
Skimmer: Magtool N-170 Heavy Bioload up to 135 gallons
Sand-Caribsea Arag-Alive Bimini Pin 20 lb
Kessel A360XE-TB Tuna Blue LED (2)
Kessil AP700 Mounting Arm
Eheim Jaga Heater 125W
Classic Stand 48x24x36
Planet 120/140 Glass Top 3 pc set. I decided to save money and not get a wooden canopy

10 day Update
I finally got the salinity stabilized. It seems as if the company who sold me the tank did not test their water. (A lesson for those new to the hobby). My tank is doing okay and seems to be cycled. This is because I used live sand, some rock and water from the old tank and bacteria. However, I will continue to work on the water chemistry. If the water chemistry improves, I now need to test the pH. I will introduce items slowly this week. One fish and coral at a time. I need to make sure that the tank can handle the bioload. I put in 2 chromis ( I made sure that there was 0 ammonia before I put them in)and the the ammonia and nitrate levels are still okay. However I need to increase the alkalinity. As I stated my main focus now is water chemistry and matching the conditions of the old tank in preparation for transfer. I have attached a pictures of the tank. I have started to aquascape. I am dosing with ALL in Reef but the Magnesium is getting a little high. Lesson learned for newbees, please make sure you start off with the best water! I have attached pictures and I also included a picture of my fish and corals who are waiting to be transferred.

2 Questions
1: I have a glass top that was ordered. Now I am finding out that I should not have ordered a glass top because it will interfere with light transmission. I will have to remove the top, increase the light intensity or order another top (screen or someone said something from Crackin. What do you suggest?
2. Is it detrimental that the magnesium is higher than normal? I need to keep dosing to increase calcium and alkalinity before I transfer.
3. I have a big black damsel that I have had for a couple of you. He was very small when I puchased him. He thinks that he is the boss of the tank and makes sure that for 2 days, new fish realizes that. After 1-2 days he leaves them alone. Someone suggested that I remove him, someone else said add him to the new tank last. I do not want to remove him, any advide on the damsel?

Nitrate 4
Ammonia 0
Salinity 1.025
Magnesium 1410
Calcium 350 - another test said 370
Phosphate 0
alkalinity/KH 10,7
Temperature 79 degrees

Beginning of Transfer
Dear All I am provided an update on my new Planet 120 gallon Aquarium on day. Starting 4 days ago I have slowly began to transfer fish an corals from my 65 gallon to the 120.
The 120 gallon has in it the following:
1 Goby
2 small chromis
4 turbo snails
3 bubble tip anemone
2 rock flower anemone
1 leather coral
3 small mushrooms
1 red sps coral (forgot the name)
live rock (some rock from the old tank)
live sand

My parameters are the following

Calcium 420
Salinity 1.026
Alkalinity 7.7
Ammonium 0
Magnesium 1350
Nitrate 5.0
phosphate .5 but looks like .25.
Temp 79.5

Question
1. The alkalinity of my old tank is 10.3. Should I try to raise the alkalinity of my new tank or simply drip acclimate the fish? The goby that came from the old tank is fine.

2. I have some diatoms..not bad but they are on the sand, a few on the rocks and on the glass. Looks like light powder. Should I leave them away and let them go away on there own or go cyclopods? Will they go away as I add more fish? Will they harm the fish or corals. It looks a little better than yesterday.

3. I hope to transfer 7 fish ( 2 clownfish, blue hippo, peppermint hogfish, foxface and a damsel, cleaner wrasse and about 4 corals over the next two days. I worry about making sure they get enough food in the new tank without me creating a bio overload and raising ammonia. What do you suggest?

4. My big damsel used to be territorial in the old tank. I have had him since he was a baby. I do not want to give him away. Should I simply transfer him last to prevent him from being territorial in the new tank in case I want to add another fish? In the old tank he would chase for about 2 days and then leave them along.


I attached a a picture of the new tank and one or two of the items in it. I also attached a picture showing the brown powder (diatoms) on the sand and a picture of my fish waiting to be transferred and the other corals. Hello my tank has cycled, working on the diatoms which seems manageable. I am working hard on raising alkalinity from now 6.7 to 8.5. This is keeping me from transferring the remainder of the fish and corals. I am dosing with Seschem fusion 2 and All for Reef. Lesson for new reefers! If a company is setting up your tank please ask for the parameters of the water. The water that was used for my 120 gallon tank was completely off parameters! Now I am trying to fix it

 

[ChrisfromBrick]

I love that branch rock!

1: I have a glass top that was ordered. Now I am finding out that I should not have ordered a glass top because it will interfere with light transmission. I will have to remove the top, increase the light intensity or order another top (screen or someone said something from Crackin. What do you suggest?
Toplids or Walter lids-polycarbonate is used. Walter is cheaper than toplids
2. Is it detrimental that the magnesium is higher than normal? I need to keep dosing to increase calcium and alkalinity before I transfer.
Probably not
3. I have a big black damsel that I have had for a couple of you. He was very small when I puchased him. He thinks that he is the boss of the tank and makes sure that for 2 days, new fish realizes that. After 1-2 days he leaves them alone. Someone suggested that I remove him, someone else said add him to the new tank last. I do not want to remove him, any advide on the damsel?
In that size tank, I would just leave him.

 

[BryanM]

Question
1. The alkalinity of my old tank is 10.3. Should I try to raise the alkalinity of my new tank or simply drip acclimate the fish? The goby that came from the old tank is fine.

2. I have some diatoms..not bad but they are on the sand, a few on the rocks and on the glass. Looks like light powder. Should I leave them away and let them go away on there own or go cyclopods? Will they go away as I add more fish? Will they harm the fish or corals. It looks a little better than yesterday.

3. I hope to transfer 7 fish ( 2 clownfish, blue hippo, peppermint hogfish, foxface and a damsel, cleaner wrasse and about 4 corals over the next two days. I worry about making sure they get enough food in the new tank without me creating a bio overload and raising ammonia. What do you suggest?

4. My big damsel used to be territorial in the old tank. I have had him since he was a baby. I do not want to give him away. Should I simply transfer him last to prevent him from being territorial in the new tank in case I want to add another fish? In the old tank he would chase for about 2 days and then leave them along.

Assuming the fish are still in 10.3 alk, I would definitely raise the alk of the new tank before transfer.

I don't know about the diatoms.

I would feed as you fed previously. I feed my fish 3x a day.

I would defer to others that have more experience with fish regarding the damsel. Your plan for the new tank seems fine to me, its just what should you do if you add new fish later? I'm not sure.

 

[Lisa Cain]

Dear All posting my latest update 1/24/2026 on 1/4/2026 the tank was 26 days old. All is well as of now. Keeping my fingers crossed. The key to success thus far is testing water parameters and keeping everything clean inclusive of water changes. Pictures are below.