The blue lamp is almost certainly going to be giving off heat aswell.
For your tortoise to be able to control it's body temperature properly it needs a cooler end and a warmer end to it's enclosure, ideally the heat source should be at one end and thermostatically controlled.
You can use a visible heatlamp for raising temperatures during the day and if required a ceramic or red heatlamp can be used overnight.
To thermoregulate your tortoise will move in and out of different temperature zones when it needs to, if these arent available, or the whole enclosure is heated to a constant temperature then he may have problems.
Here's some super basic simplified info to start with incase you need it
"Common Name: Horsfields/Russian Tortoise
Scientific name: Testudo horsfieldi
Originates From This tortoise is Asiatic, being found although in relatively low numbers, in Afghanistan, Pakistan, Eastern Iran, Western China and throughout the southerly regions of Russia.
Most Active During: Daylight, Diurnal
Size: Females 8-10" Males slightly smaller around 8"
Sexing: Males have a longer more pointed tail which is usually held sticking directly out, whereas females have shorter stubbier tails which are often curved round within the boundary of the shell.
Water Supply: These tortoises must have a very shallow low sided water dish in which to bathe and possibly drink from at all times. They need no more than a centimetre of water, water should be replaced each day and immediately if fouled by the tortoise.
Substrate: My recommended substrate is "Tortoise Life" compacted grass pellet, which allow the tortoise to burrow as it is naturally inclined to do but without risk of internal damage if eaten. Care must be taken to ensure that substrate does not get ingested along with the animals food, this can be done by the use of a large flat low sided feeding dish.
UV Lighting: Horsfields Tortoises require UV lighting in order to synthesise Vitamin D3 and therefore utilise Calcium in their diet for growth. An 8.0 tube placed within at least 12" of the basking site is required. UV tubes should be on for 12-14 hours per day and should be replaced every 6-8 months.
Humidity Requirements: Their natural environment is semi arid, in the wild they dig deep burrows in order to increase humidity and avoid dehydration. As long as a captive tortoise is allowed to bathe in chin-deep water, or if it does not naturally choose to it should be bathed three times a week, your will not need to worry about possible dehydration.
Temperatures and Heating Equipment: Horsfields tortoises require a basking spot of around 95F and daytime temperatures ranging between 80-90F. Nighttime temperatures should be maintained between 70-75F. Tortoises are more suited to heating from above, so either an incandescent or ceramic lamp should be used to maintain the temperatures, heat mats are not really suitable. Daytime temperatures should coincide with the hours in which the UV tube is being used.
Housing: These tortoises are best housed in an open topped tortoise table of a minimum area of 2'x4'.
Decor: No other furnishings than a hidebox in both the cooler and warmer areas of the vivarium are required, these tortoises do not climb and their movement will only be hindered by the addition of fake plants, rocks or wood. Alfalfa hay can be used in the cooler end as a sleeping area for your tortoise.
Diet: 100% Herbivorous. These Tortoises should be fed a diet of high fibre and calcium, low protein foods. Watery foods such as lettuce, cucumber, tomatoes and fruits are unsuitable. The foods should be dry since this animal is adapted to getting the most out of high fibre dry foods. Suitable foods include; Grass hay, alfalfa hay, grass, dandelion, clover, mulberry or grape leaves, butternut squash, curly kale and loose leaved cabbage. Spinach and Broccoli are a good addition in smaller amounts, the following can be fed much more occaisonally; greenbeans, carrots, squash, hibiscus. Calcium and multivitamin supplimentation of foods is essential to your tortoises growth."
Lotte*