pH, temperature and refugium lighting quedtions


Reefing newb
Ok, I am extremely new at saltwater aquariums. I spent a number of weeks reading all about saltwater tanks to try prepare myself as much as possible before I started. I recently purchased a 45g bowfront with 30g sump second hand. In the sump I have a protein skimmer (that I've been adjusting and seems to be doing its job), refugium with sand, live rock and a light, 200w heater and a small filter with activated carbon. In the main tank I have a DSB (5") with 75lbs of live rock that has now been in the tank for 3-4 weeks. The top of my main tank is covered with glass except for a 5" strip across the back of the tank, and I put clear plastic across the top of my sump to reduce evaporation because I was loosing so much water. Everything seems to be running well and doing it's job. However, I have a few questions.

1. I am having a hard time keeping my temperature constant. The tank is in a room that I usually keep the windows and doors closed to to keep my dog out. I have been monitoring the temperature for a number of days now and it has fluctuated anywhere form +/- 2-3 degrees in some cases. I am not sure why this is. The heater seems to be working properly. I know it could have to do with the room being closed/air movement, temperature fluctuations in the house and water surface exposure but I was wondering if anyone had any advice for ideal conditions or what I should try.

2. This is somewhat minor but the setup I purchased came with a small clip on light for the refugium in the sump. I don't know what kind of bulb he had in it but I notice the temperature increase slightly when the light is on. I was wondering what kind of light I should have down there and what kind of schedule it should be on? I have been keeping the lights in my main tank off for the most part to prevent an algae bloom while the tank cycled.

3. This is probably my biggest and most immediate concern. Ok. I have run water tests twice since adding the live rock and both tests returned the same results. I am using an API test kit that came with the tank I purchased. My salinity is 25 (checked with a hydrometer) and I have the temperature set to 82 Fahrenheit (I read setting it slightly higher would increase the cycling rate). Here's the results:

pH - <7.4
Ammonia ~ 0.25 ppm
Nitrite - 0
Nitrate - 0
Phosphate - 0
kH ~ 5.5 (ELOS test kit)

One test was done on the 10th of June and the second was done today (the 30th). My obvious concern is with he pH/kH. I tried using an API water buffer to increase the pH in between tests (a single dose) but it doesn't seem to have made a difference. I'm embarrassed to say I did not check anything other than temperature and salinity prior to adding my liverock, but want to make SURE everything is ok before I start adding inverts/fish. The water I use is tap water, however it is not city water because I live in the country. It comes from lake superior (freshwater lake) and is filtered but not treated to any extent. I am fairly certain this was probably my main mistake and have every intention of purchasing an RO/DI unit. But I want to know how I can correct this issue with/without the unit, what is a good RO/DI unit and will my live rock be ok????

After I added the rock I had some brown algae growth on it and in the sand which seems to have stopped growing since I reduced the time I ran my lights but is still present. Should I still be running my lights at all right now?

Any and all advice would be greatly appreciated. I am very eager to get these issues fixed so I can finally add fish/inverts but want to do things right.
I would remove the glass tops. Evaporation is good -- that's what cools your tank. You will have to top off to make up for the evaporated water (use fresh water to top off, not saltwater). Glass tops inhibit gas exchange, raise temperature and collect salt creep. And it doesn't help with your pH.

I think removing the glass tops will help stabilize your temperatures. A 2 to 3 degree change within a 24 hour period is not too bad, but you'd really like it to stay stable if possible. But that's almost impossible to do. ;)

Setting your temperature higher won't help the cycle go faster. Try to get it down to the 78 to 80 degree range if possible. If you have to keep it at 82, having it stable at 82 is better than it dropping and rising every day.

You should run the refugium opposite of the display tank. So if you run the main tank lights for 12 hours during the day, you would run the refugium light the opposite 12 hours at night. Running an opposite light schedule stabilizes the pH of your tank.

Your pH is very low. But I wouldn't worry about it right now since it looks like your tank just started cycling. Your parameters will be all over the place during the cycle, and adding buffer will only screw with things even more. Wait it out. It will go back up as your tank finishes cycling.

I assume you mean your salinity is at 1.025? If so, that's perfect.

You don't want to add any animals until your ammonia is at zero. Did you ever see the nitrites spike? If not, I would throw a raw piece of shrimp from the grocery store in the tank just to make sure it has had a strong cycle. If ammonia only ever got up to .25 and nitrites never spiked, then you may see a really bad cycle when you add fish.
Thank you very much for your response. I did mean 1.025 for the specific gravity, must have had a little brain lapse there. I never saw the nitrites spike so I will be trying the raw shrimp in the next few days. I reduced my temp to 79 and will set my refugium light on a timer opposite of my main lights. I will also remove the glass tops. I still have a few questions, sorry for the barrage :?

1. Should I also remove the plastic cover I have over the sump?
2. If I do remove the glass top, should I put something in its place to prevent fish from jumping out?
3. For my lights, should I be running them normally, barely, or not at all while waiting for the tank to cycle? In relation to algae blooms of course.
4. Is there a certain kind of bulb/temperature of bulb I should have for my refugium?
5. For water top off, am I foolish to continue using the lake water I get through my tap? I haven't actually run any tests on it yet but I know the pH is typically in the 7.1 - 7.4 range.
6. Should my live rock be aright despite the low pH?

Thank you again for your replies...
I don't think the plastic cover over the sump matters. You can leave that on. Having the display tank open is more important, as as long as your temperatures stay good, I see no reason why the sump can't be covered.

Fish can and do jump. Check out this thread for an idea of a mesh top instead of a solid top:

You don't need to run your lights during the cycle. You are correct that it will create algae. But, you are going to get algae anyways when you do turn them on down the road. The cycle will progress with or without lights, so that's up to you. Some people like to see their tank, even if there are only rocks in it.

For a refugium, I always had the best luck with a regular CFL (squiggly) bulb from the hardware store. You will be growing macroalgae in the refugium, and most types of algae don't require any sort of special light to grow. There are specific lights made for refugiums that take special bulbs -- is that the kind that you have? I used a clamp-on shop light from the hardware store.

You should get an RODI unit as soon as you can. That is one of the most important pieces of equipment in the hobby. If you put garbage in your tank, you will get garbage out. Now some tap water is much better than others. But you don't know for sure what is in your tap water. If you can't get an RODI unit right away, you should be using bottled RO water, which you can buy at the grocery store, Walmart or fish store. Tap water should only be used as a last resort, as it normally contains all sorts of nasty stuff that is bad for your tank. If you continue to use tap water, it is likely that you will battle non-stop algae problems. Here is an article to read:

Your live rock should be fine in spite of the pH.
Wow again thank you for your prompt and informative reply. I just checked and have a 16w 6500k "squiggly" bulb in a reflective enclosure for my refugium that I have now programmed to run opposite the main lights so that should be good now. I removed the glass canopy and checked out that link you sent. Very cool and easy to do/inexpensive by the looks of it. I'll have to see how I can make that work on a bowfront but will definitely be putting something on before adding fish! I did keep the cover on the sump though. I will be adding the shrimp tonight and will monitor the levels throughout the week As far as the RO/DI unit, I am willing to place an order today, but was wondering if anyone had some suggestions as to what's a good unit in terms of quality and cost? And what brings the pH up to 8.0 when you use the RO water? Is that the salt that does that? Thanks again in advance :)
Look at the 100 gpd units at Bulk reef supply, Buckeye Field Supply or even eBay. You could even go with a 50 gpd unit. Make sure you DO get one with a pressure gauge though. Gotta have 35 psi to get any water from them. 60 psi seems to be the best.